r600g,radeonsi: switch all occurences of array_size to util_max_layer

r600g,radeonsi: switch all occurences of array_size to util_max_layer

This fixes 3D texture support in all these cases, because array_size is 1
with 3D textures and depth0 actually contains the "array size".
util_max_layer is universal and returns the last layer index for any texture
target.

A lot of the cases below can't actually be hit with 3D textures, but let's
be consistent.

This fixes a failure in:
    piglit layered-rendering/clear-color-all-types 3d single_level
for r600g and radeonsi, which was caused by an incorrect CMASK size
calculation.

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>