crossystem: arm: Make FDT_BASE_PATH /proc/device-tree

Hard-coding to /proc/device-tree/firmware/chromeos won't let us read
device-tree properties outside of /firmware/chromeos.

The follow-on CL reads from /firmware/coreboot.

BUG=b:187790074,b:270917040
BRANCH=none
TEST=CQ passes

Change-Id: I752aa5a1e20db1dad7f2508852c7a1c982a4bcb4
Signed-off-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4045046
Reviewed-by: Julius Werner <jwerner@chromium.org>
(cherry picked from commit edcc75666d8fab2e1be895ac87af87ee74ec0079)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4300249
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
1 file changed