Remove unused include path.
Remove unused include path.

This path doesn't exists in the repo so this patch removes it from the
Makefile:
  firmware/arch/${FIRMWARE_ARCH}/include

BUG=None
BRANCH=None
TEST=./emerge_test

Change-Id: I8b5461ee0ddfa0aa8d31bc6d2b981912a9ccde58
Reviewed-on: https://chromium-review.googlesource.com/214392
Reviewed-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>
Commit-Queue: Alex Deymo <0bb68aca05e38f8ef6dec21b678bbb2a1f313713@chromium.org>
Tested-by: Alex Deymo <0bb68aca05e38f8ef6dec21b678bbb2a1f313713@chromium.org>

acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference,coreboot/vboot,coreboot/vboot,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference