lib/igt_kms: Don't assert on non-existent plane

Skip when a test can't find a plane by the index. Previously
in commit 5426dc0a889a ("lib/kms: Skip rather than fail when
a suitable plane can't be found") we added similar handling for
tests trying to find a non-existent plane by type. Saves from
every test with hardcoded plane numbers having to check the
number of planes available.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>
1 file changed