anv: Check that in_fence fd is valid before closing it.

Probably harmless, but will overwrite errno with a failure status
code.  Reported by coverity.

CID 1416600: Argument cannot be negative (NEGATIVE_RETURNS)
Fixes: 5c4e4932e02 (anv: Implement support for exporting semaphores as FENCE_FD)
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
1 file changed