rollback: Remove unnecessary shadow variable
rollback: Remove unnecessary shadow variable

BRANCH=none
BUG=none
TEST=make buildall -j
TEST=make BOARD=nocturne_fp
     ssh dut1 mount -oremount,rw /
     scp build/nocturne_fp/ec.bin dut1:~/
     # CCD Cr50 Console
     wp disable
     # Back to host
     ssh dut1 flash_fp_mcu '~/ec.bin'
     ssh dut1 touch /opt/google/biod/fw/.disable_fp_updater
     ssh dut1 rm -rf '/var/log/*'
     ssh dut1 reboot
     # FPMCU UART Console
     > version
     > rollback

Change-Id: If88fda706198184abfc47188eec31f7817c986da
Signed-off-by: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1808066
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

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