drm/xe: Fix xe_mocs.h

We don't need to include <linux/types.h>.
We don't use struct xe_exec_queue here.
We should sort forward declarations.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240506205254.2659-1-michal.wajdeczko@intel.com