vboot: deprecate ARM's VbGetVarGpio
vboot: deprecate ARM's VbGetVarGpio

This was originally used for some U-Boot devices which have
already reached AUE.

Keep gpiod_read (the current method), and VbGetPlatformGpioStatus
(deprecated, but still used in current devices).

BUG=chromium:942901
TEST=make clean && make runtests
BRANCH=none

Change-Id: I2a7b97f2ead0294027407cb4e9349cc5265f8f82
Signed-off-by: Joel Kitching <c2feea8c1334a0d339e816ae4c7c9ecfa9b30a91@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1539434
Tested-by: Joel Kitching <c2feea8c1334a0d339e816ae4c7c9ecfa9b30a91@chromium.org>
Commit-Queue: Joel Kitching <c2feea8c1334a0d339e816ae4c7c9ecfa9b30a91@chromium.org>
Reviewed-by: Julius Werner <4d12f06cff3725783b352157673a720bc67c4afe@chromium.org>
Reviewed-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>

coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot