drm/xe/oa: Don't reset OAC_CONTEXT_ENABLE on OA stream close

Mesa testing on Xe2+ revealed that when OA metrics are collected for an
exec_queue, after the OA stream is closed, future batch buffers submitted
on that exec_queue do not complete. Not resetting OAC_CONTEXT_ENABLE on OA
stream close resolves these hangs and should not have any adverse effects.

v2: Make the change that we don't reset the bit clearer (Ashutosh)
    Also make the same fix for OAC as OAR (Ashutosh)

Bspec: 60314
Fixes: 2f4a730f ("drm/xe/oa: Add OAR support")
Fixes: 14e077f8 ("drm/xe/oa: Add OAC support")
Closes: #2821


Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240924213713.3497992-1-ashutosh.dixit@intel.com