teams: refactored db code.

pkg/services/sqlstore/migrations/team_mig.go

@@ -56,8 +56,6 @@ func addTeamMigrations(mg *Migrator) {
 	}))
 
 	mg.AddMigration("Add column permission to team_member table", NewAddColumnMigration(teamMemberV1, &Column{
-		Name:     "permission",
-		Type:     DB_BigInt,
-		Nullable: true,
+		Name: "permission", Type: DB_SmallInt, Nullable: true,
 	}))
 }