Input: cros_ec_keyb - add 3 buttons for monitor function

Add 3 extra buttons: 'brightness up', 'brightness down'
and 'screen lock' to support monitor manipulating function.

Signed-off-by: Joe Wu <joewu@msi.com>
Link: https://lore.kernel.org/r/e23628e2cb464d238eb1c33a9e1e516b@msi.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>