vfio: platform: No need to check res again

In function vfio_platform_regions_init(),we did check res implied
by using while loop,
so no need to check whether res be null or not again.

No functional change intended.

Signed-off-by: Angus Chen <angus.chen@jaguarmicro.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20230107034721.2127-1-angus.chen@jaguarmicro.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>