writeprotect.c: skip unnecessary writes

* Don't write register because of RO and OTP bits.
* Skip the write of RW bits if register state wouldn't change by it.

Change-Id: I81d2d3fc0a103ee00ced78838d77fe33a9d3056a
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/66754
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Original-Reviewed-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71004
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed