drm/xe: Fix modpost warning on xe_mocs kunit module

$ make W=1 -j100 M=drivers/gpu/drm/xe
MODPOST drivers/gpu/drm/xe/Module.symvers
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/xe/tests/xe_mocs_test.o

Fix is identical to '1d425066 ("drm/xe: Fix modpost warning on kunit
modules")'.

Fixes: a6a4ea6d

 ("drm/xe: Add mocs kunit")
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>