intel/dev: Add devinfo::mem to store i915 regions information

intel/dev: Add devinfo::mem to store i915 regions information

Reworks:
 * Lionel: Change check on memory region valid to vram size
 * Jordan: Drop regions.valid (Lionel implemented a fallback)
 * Jordan: Rename devinfo::regions to devinfo::mem.
 * Jordan: Add devinfo::mem::use_class_instance
 * Add mesa_logw for lmem requiring regions. (s-b Lionel)

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17075>