For the upcoming header restore vendor command implementation there is
a need to allow rw access to the alternative RO area.
A static function for this is available in upgrade_fw.c, let's make it
available to other users.
BRANCH=cr50
BUG=b:35580805
TEST=verified that it is still possible to update the RO.
Change-Id: I879804ff180c5d00cf6860ce5669f2fe48731832
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/457501
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>