platform/x86: uniwill-laptop: Mark EC_ADDR_OEM_4 as volatile

platform/x86: uniwill-laptop: Mark EC_ADDR_OEM_4 as volatile

It turned out that EC_ADDR_OEM_4 also contains bits with a volatile
nature. Mark the whole register as volatile to prepare for the usage
of said bits. This also means that we now have to save/restore the
touchpad toggle state ourself.

Reviewed-by: Werner Sembach <wse@tuxedocomputers.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20260512232145.329260-7-W_Armin@gmx.de
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>