cpu/allwinner/a10: Refactor and document pinmux API

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

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>
3 files changed