vfio/type1: Fix vfio_find_dma_valid return

vfio/type1: Fix vfio_find_dma_valid return

vfio_find_dma_valid is defined to return WAITED on success if it was
necessary to wait.  However, the loop forgets the WAITED value returned
by vfio_wait() and returns 0 in a later iteration.  Fix it.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/r/1629736550-2388-1-git-send-email-anthony.yznaga@oracle.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>