drm/xe: Use XE_REG/XE_REG_MCR

drm/xe: Use XE_REG/XE_REG_MCR

These should replace the _MMIO() and MCR_REG() from i915, with the goal
of being more extensible, allowing to pass the additional fields for
struct xe_reg and struct xe_reg_mcr. Replace all uses of _MMIO() and
MCR_REG() in xe.

Since the RTP, reg-save-restore and WA infra are not ready to use the
new type, just undef the macro like was done for the i915 types
previously. That conversion will come later.

v2: Remove MEDIA_SOFT_SCRATCH_COUNT/MEDIA_SOFT_SCRATCH re-added by
    mistake (Matt Roper)

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230427223256.1432787-8-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>