drm/xe: make change ccs_mode a synchronous action

drm/xe: make change ccs_mode a synchronous action

If ccs_mode is being modified via
   /sys/class/drm/cardX/device/tileY/gtY/ccs_mode
the asynchronous reset is triggered and the write returns immediately.

With that some test receive false information about number of CCS engines
or even fail if they proceed without delay after changing the ccs_mode.

Changing the ccs_mode change from async to sync to prevent failures in
tests.

Signed-off-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Fixes: f3bc5bb4d53d ("drm/xe: Allow userspace to configure CCS mode")
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211111727.1481476-3-maciej.patelczyk@intel.com
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>