stm32mon: : fix coverity scan issue on a write_wrapper() call
stm32mon: : fix coverity scan issue on a write_wrapper() call

This CL fixes coverity scan check issue, which points that there is
a call to write_wrapper() missing return value checking.
This was added by crrev.com/c/1540496, which is about a sending
garbage byte to DUT to avoid reTIMEOUT response repeating.

BUG=b:131231369
BRANCH=none
TEST=ran flash_ec on scarlet at 9600 bps.

flash_ec --board scarlet --image ${IMG} --bitbang_rate 9600

Change-Id: I25ea43ae13d9fbf16b90fba4030c9bb640498453
Signed-off-by: Namyoon Woo <e8732cefb861f07768f47df788a8e8eb75efc09a@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1588497
Legacy-Commit-Queue: Commit Bot <5c2bf027dc5cc7ef186314391646e49f6866dc00@chromium.org>
Reviewed-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec