X60: trigger save cmos on volume/brightness change

X60: trigger save cmos on volume/brightness change

Change-Id: I020e06bc311c4e4327c9d3cf2c379dc8fe070a7a
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/25
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>