drm/xe/mtl: Add support to get C6 residency/status of MTL

drm/xe/mtl: Add support to get C6 residency/status of MTL

Add the registers to get C6 residency of MTL SAMedia and
C6 status of MTL gts

v2:
   - move register definitions to regs header (Anshuman)
   - correct reg definition for mtl rc status
   - make idle_status function common (Badal)

v3:
   - remove extra line in commit message
   - use only media type check in initialization
   - use graphics ver check (Anshuman)

v4:
   - remove extra lines (Anshuman)

Bspec: 66300
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>