drm/i915/mtl: Add engine TLB invalidation

MTL's primary GT can continue to use the same engine TLB invalidation
programming as past Xe_HP-based platforms.  However the media GT needs
some special handling:
 * Invalidation registers on the media GT are singleton registers
   (unlike the primary GT where they are still MCR).
 * Since the GSC is now exposed as an engine, there's a new register to
   use for TLB invalidation.  The offset is identical to the compute
   engine offset, but this is expected --- compute engines only exist on
   the primary GT while the GSC only exists on the media GT.
 * Although there's only a single GSC engine instance, it inexplicably
   uses bit 1 to request invalidations rather than bit 0.

v2:
 - Add a 'regs == xelpmp_regs' condition to the GSC instance handling.
   If the registers change on a future platform, the GSC-specific
   handling is likely to change as well.  (Andrzej)

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230224012009.3594691-1-matthew.d.roper@intel.com