anv: Add a new anv_surface_state struct

anv: Add a new anv_surface_state struct

This struct represents a full surface state including the addresses of
the referenced main and auxiliary surfaces (if any).  This makes
relocation setup substantially simpler and allows us to move 100% of the
surface state setup logic into anv_image where it belongs.  Before, we
were manually fishing data out of surface states when emitting
relocations so we knew how to offset aux address.  It's best to keep all
of the surface state emit logic together.  This also gets us closer, at
least cosmetically, to a world of no relocations where addresses are
placed in surface states up-front.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>