libpayload: Bring keyboard_wait_write() back

Code is using it...

Change-Id: I6894b45cbbf70c8e7ce37ce18d93cadf0ea9fbfc
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/4649
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Nico Huber <nico.h@gmx.de>
1 file changed