drm/xe: Add locks in gtidle code

drm/xe: Add locks in gtidle code

The update of the residency values needs to be protected by a lock to
avoid multiple entrypoints, for example when multiple userspace clients
read the sysfs file. Other in-kernel clients are going to be added to
sample these values, making the problem worse. Protect those updates
with a raw_spinlock so it can be called by future integration with perf
pmu.

Suggested-by: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250110173308.2412232-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>