drm/xe/rtp: (De-)whitelist OA registers for all hwe's for a gt

drm/xe/rtp: (De-)whitelist OA registers for all hwe's for a gt

Whitelist or de-whitelist OA registers for all hwe's on the gt on which the
OA stream is opened. This simplifies the case where an oa unit has 0
attached hwe's (but which monitors OA events on the associated GT).

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/20260615224227.34880-8-ashutosh.dixit@intel.com