drm/xe: Get rid of MAKE_INIT_EXIT_FUNCS

There is not much of a benefit from using that macro as of now and it
hurts grepability or other ways of cross-referencing.

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>