Simplify error returns (gosimple)

This fixes:
pkg/api/avatar/avatar.go:261:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/log/file.go:102:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/metrics/graphitebridge/graphite.go:298:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/provisioning/provisioning.go:23:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/alert_notification.go:27:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/alert_notification.go:27:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/annotation.go:105:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/annotation.go:105:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard.go:351:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard.go:435:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard_acl.go:38:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard_acl.go:38:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/stats.go:22:2: 'if err != nil { return err }; return err' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/team.go:213:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:256:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:256:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:274:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:274:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:482:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:482:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)

pkg/services/sqlstore/user.go

@@ -253,11 +253,8 @@ func ChangeUserPassword(cmd *m.ChangeUserPasswordCommand) error {
 			Updated:  time.Now(),
 		}
 
-		if _, err := sess.Id(cmd.UserId).Update(&user); err != nil {
-			return err
-		}
-
-		return nil
+		_, err := sess.Id(cmd.UserId).Update(&user)
+		return err
 	})
 }
 
@@ -271,11 +268,8 @@ func UpdateUserLastSeenAt(cmd *m.UpdateUserLastSeenAtCommand) error {
 			LastSeenAt: time.Now(),
 		}
 
-		if _, err := sess.Id(cmd.UserId).Update(&user); err != nil {
-			return err
-		}
-
-		return nil
+		_, err := sess.Id(cmd.UserId).Update(&user)
+		return err
 	})
 }
 
@@ -479,10 +473,7 @@ func SetUserHelpFlag(cmd *m.SetUserHelpFlagCommand) error {
 			Updated:    time.Now(),
 		}
 
-		if _, err := sess.Id(cmd.UserId).Cols("help_flags1").Update(&user); err != nil {
-			return err
-		}
-
-		return nil
+		_, err := sess.Id(cmd.UserId).Cols("help_flags1").Update(&user)
+		return err
 	})
 }