Fix ambiguous cast

The conversion from uint64_t to QFlags is now ambiguous, but since
we need an int QVariant in the end anyway, we can cast directly to that.

Change-Id: I4478efa2b293a59b47c46d27346b56eab48b3278
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>