i965/miptree: Drop miptree_array_layout in get_isl_dim_layout()

i965/miptree: Drop miptree_array_layout in get_isl_dim_layout()

This was only needed for checking gen6 stencil which is already
using isl. One could delete GEN6_HIZ_STENCIL layout altogether
but that will be gone with the rest after a while anyway.

The dim_layout converter is needed even after transition to isl
when setting up surface states - see brw_emit_surface_state().
Hence dropping the unneeded argument separately.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Topi Pohjolainen <topi.pohjolainen@intel.com>