Include a function to multiplex more than one pin at a time. This is useful for peripherals that have the same function number for all their pins. Since we now have two functions for muxing pins, also document them. Change-Id: I53997cc3a2586e3cf749cd672f69fb427659c67f Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com> Reviewed-on: http://review.coreboot.org/4565 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>