drm/xe: Move LNL scheduling WA to xe_device.h

drm/xe: Move LNL scheduling WA to xe_device.h

Move LNL scheduling WA to xe_device.h so this can be used in other
places without needing keep the same comment about removal of this WA
in the future. The WA, which flushes work or workqueues, is now wrapped
in macros and can be reused wherever needed.

Cc: Badal Nilawar <badal.nilawar@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
cc: stable@vger.kernel.org # v6.11+
Suggested-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241029120117.449694-1-nirmoy.das@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>