drm/xe/pmu: Add GT C6 events

Provide a PMU interface for GT C6 residency counters. The interface is
similar to the one available for i915, but gt is passed in the config
when creating the event.

Sample usage and output:

	$ perf list | grep gt-c6
	  xe_0000_00_02.0/gt-c6-residency/                   [Kernel PMU event]

	$ tail /sys/bus/event_source/devices/xe_0000_00_02.0/events/gt-c6-residency*
	==> /sys/bus/event_source/devices/xe_0000_00_02.0/events/gt-c6-residency <==
	event=0x01

	==> /sys/bus/event_source/devices/xe_0000_00_02.0/events/gt-c6-residency.unit <==
	ms

	$ perf stat -e xe_0000_00_02.0/gt-c6-residency,gt=0/ -I1000
	#           time             counts unit events
	     1.001196056              1,001 ms   xe_0000_00_02.0/gt-c6-residency,gt=0/
	     2.005216219              1,003 ms   xe_0000_00_02.0/gt-c6-residency,gt=0/

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250124050411.2189060-6-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>