futility: updater: Stop looking for zephyr.bin
futility: updater: Stop looking for zephyr.bin

In CL:3788136 the zephyr EC image is renamed from zephyr.bin to ec.bin.
Therefore we don't need to check the existence of zephyr.bin anymore.

BUG=b:239887568
TEST=make runtests -j
BRANCH=none

Cq-Depend: chromium:3788136
Change-Id: Icd82baff93d2019cfd90b982e9c25b45cbf611c3
Signed-off-by: Yu-Ping Wu <e17b963d2ce5bddd1fecae25c320252b132e804d@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3795458
Reviewed-by: Hung-Te Lin <8a7fce4940baad93a69f5073b383c85deed9d9c4@chromium.org>
Reviewed-by: Yidi Lin <537bc4b71aa0f16928afbddc263aa3534c6afc02@chromium.org>

coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot