util: make flash_ec tolerant with dummy npcx_uut chip
util: make flash_ec tolerant with dummy npcx_uut chip

flash_ec fails when npcx_uut chip in a bad status doesn't respond
at all, especially upon ec_flash_size query.
This patch subpress the exit on ec_flash_size query failure, because
that information is not mandatory in flashing EC.

BUG=none
BRANCH=none
TEST=manualy tested on kohaku.
1. programmed kohaku EC with a wrong binary.
2. checked kohaku EC in a bad status, and was not able to respond.
3. ran flash_ec and checked flash_ec finished EC FW program.
   e.g. flash_ec --board kohaku --image ${IMG}
4. read EC firmware back.
   e.g. flash_ec --board kohaku --read ${TMP_IMG}

Change-Id: Ic853dd9f827217621cd598c799c68fbbf970078a
Signed-off-by: Namyoon Woo <e8732cefb861f07768f47df788a8e8eb75efc09a@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1753009
Reviewed-by: Paul Fagerburg <d8c44b60afb21c60f56d931aa690ca1cf34910c8@chromium.org>

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