[QtSql][QSqlTableModel] fix failure to refresh in selectRow()

Caused by missing braces, leaving the break outside the scope of the if clause.

Task-number: QTBUG-38509
Change-Id: I6b0a7f34512a3a9b0fbd790116f81f54f4a91cf0
Reviewed-by: Tobias Koenig <tobias.koenig.qnx@kdab.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Reviewed-by: Andy Shaw <andy.shaw@digia.com>