drm/xe/oa: (De-)whitelist OA registers on OA stream open/release

drm/xe/oa: (De-)whitelist OA registers on OA stream open/release

Whitelist OA registers on stream open and de-whitelist on stream
close/release. Whitelisting is only done when 'stream->sample' is
true. 'stream->sample' is only true when (a) xe_observation_paranoid is set
to false by system admin, or (b) the process is perfmon_capable(). This
therefore enforces the OA register whitelisting security requirements.

Fixes: 828a8eaf37c3 ("drm/xe/oa: Add MMIO trigger support")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patch.msgid.link/20260615224227.34880-9-ashutosh.dixit@intel.com