drm/xe: Add a wrapper for SLPC set/unset params

drm/xe: Add a wrapper for SLPC set/unset params

Also, extract out the GuC RC related set/unset param functions
into xe_guc_rc file. GuC still allows us to override GuC RC mode
using an SLPC H2G interface. Continue to use that interface, but
move the related code to the newly created xe_guc_rc file.

Cc: Riana Tauro <riana.tauro@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patch.msgid.link/20260204014234.2867763-4-vinay.belgaumkar@intel.com