drm/xe: Apply whitelist to engine save-restore

drm/xe: Apply whitelist to engine save-restore

Instead of handling the whitelist directly in the GuC ADS
initialization, make it follow the same logic as other engine registers
that are save-restored. Main benefit is that then the SW tracking then
shows it in debugfs and there's no risk of an engine workaround to write
to the same nopriv register that is being passed directly to GuC.

This means that xe_reg_whitelist_process_engine() only has to process
the RTP and convert them to entries for the hwe.  With that all the
registers should be covered by xe_reg_sr_apply_mmio() to write to the HW
and there's no special handling in GuC ADS to also add these registers
to the list of registers that is passed to GuC.

Example for DG2:

	# cat  /sys/kernel/debug/dri/0000\:03\:00.0/gt0/register-save-restore
	...
	Engine
	rcs0
		...
		REG[0x24d0] clr=0xffffffff set=0x1000dafc masked=no mcr=no
		REG[0x24d4] clr=0xffffffff set=0x1000db01 masked=no mcr=no
		REG[0x24d8] clr=0xffffffff set=0x0000db1c masked=no mcr=no
	...
	Whitelist
	rcs0
		REG[0xdafc-0xdaff]: allow read access
		REG[0xdb00-0xdb1f]: allow read access
		REG[0xdb1c-0xdb1f]: allow rw access

v2:
  - Use ~0u for clr bits so it's just a write (Matt Roper)
  - Simplify helpers now that unused slots are not written

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241209232739.147417-6-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>