i965: Fix bugs in intel_from_planar

i965: Fix bugs in intel_from_planar

This commit fixes two bugs in intel_from_planar.  First, if the planar
format was non-NULL but only had a single plane, we were falling through
to the planar case.  If we had a CCS modifier and plane == 1, we would
return NULL instead of the CCS plane.  Second, if we did end up in the
planar_format == NULL case and the modifier was DRM_FORMAT_MOD_INVALID,
we would end up segfaulting in isl_drm_modifier_has_aux.

Cc: mesa-stable@lists.freedesktop.org
Fixes: 8f6e54c92966bb94a3f05f2cc7ea804273e125ad
Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>