flash_ec: fix for SERVO_TYPE=toad
flash_ec: fix for SERVO_TYPE=toad

In CL:503475, SERVO_TYPE is initialized *after* toad cable detection.
This make flash_ec failed to update plankton EC.
This CL adjust the timing of SERVO_TYPE detection, so toad cable
detection can work properly.

BUG=b:35648297
BRANCH=plankton
TEST=utils/flash_ec --board=plankton

Change-Id: I08a11b99109454096949b3ff64ed1c4d5f9891df
Reviewed-on: https://chromium-review.googlesource.com/535381
Commit-Ready: Wei-Han Chen <5413a119f383c3f4549c3ef659403f393bf06e9d@chromium.org>
Tested-by: Wei-Han Chen <5413a119f383c3f4549c3ef659403f393bf06e9d@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