lynxpoint: provide gpio_is_native()

There's a need to determine if a specific gpio pin is
is set up to be a native function or not. Implement this.

Change-Id: I91d57a549e0f4fddc0b1849e5f74320fc839642c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/59589
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4324
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
3 files changed