anv: create a pool for indirect descriptors

anv: create a pool for indirect descriptors

We'll use the fact that the pool is aligned to 4Gb to limit the amount
of address computations to build the address in the shaders.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21645>