anv: Stop updating STATE_BASE_ADDRESS on XeHP

Now that we're using 3DSTATE_BINDING_TABLE_POOL_ALLOC to set the base address for the binding table pool separately from surface states, we don't actually need to update surface state base address anymore.

Instead, we can just set STATE_BASE_ADDRESS once at context creation, and never bother updating it again, saving some heavyweight flushes and freeing us from the need for address offsetting trickery.

This patch was originally written by Jason Ekstrand, with fixes from Lionel Landwerlin, but was targeting Icelake. Doing it there requires additional changes (15:5 -> 18:8 binding table pointer formats) which also involve some trade-offs, whereas the XeHP change is purely a win, so we'll do it here first.

+@jljusten @llandwerlin @jekstrand