drm/xe: Decouple GuC RC code from xe_guc_pc

drm/xe: Decouple GuC RC code from xe_guc_pc

Move enable/disable GuC RC logic into the new file. This will
allow us to independently enable/disable GuC RC and not rely
on SLPC related functions. GuC already provides separate H2G
interfaces to setup GuC RC and SLPC.

Cc: Riana Tauro <riana.tauro@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patch.msgid.link/20260204014234.2867763-2-vinay.belgaumkar@intel.com