i965: Fix aux-surface size check

i965: Fix aux-surface size check

The previous commit reworked the checks intel_from_planar() to check the
right individual cases for regular/planar/aux buffers, and do size
checks in all cases.

Unfortunately, the aux size check was broken, and required the aux
surface to be allocated with the correct aux stride, but full image
height (!).

As the ISL aux surface is not recorded in the DRIimage, we cannot easily
access it to check. Instead, store the aux size from when we do have the
ISL surface to hand, and check against that later when we go to access
the aux surface.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Fixes: c2c4e5bae3ba ("i965: Fix bugs in intel_from_planar")
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>