drm/xe/xe_pmu: Acquire forcewake on event init for engine events

drm/xe/xe_pmu: Acquire forcewake on event init for engine events

When the engine events are created, acquire GT forcewake to read gpm
timestamp required for the events and release on event destroy. This
cannot be done during read due to the raw spinlock held my pmu.

v2: remove forcewake counting (Umesh)
v3: remove extra space (Umesh)
v4: use event pmu private data (Lucas)
    free local copy (Umesh)

Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250224053903.2253539-6-riana.tauro@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>