intel/genxml: Fix pixel hashing 3DSTATE_3D_MODE field definitions for Gen12 and Gen12.5.
The former "Subslice Hashing Mode" field is no longer used by the
hardware, Gen12 parts always do 16x16 subslice pixel hashing -- Remove
it since it's no longer useful. In addition add a couple of bits that
will be useful in order to make some adjustments to the default pixel
pipe hashing behavior.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8749>