this driver adds the capability to update the firmware of the anx3429
TCPC.  the driver will be registered with vboot to be invoked during
software sync, much like the ps8751 TCPC update driver.

BRANCH=none
BUG=b:35586895
TEST=in conjunction with follow-on CLs, verified we can update the
	OTP.  for now, only tested with a test pattern being
	programmed into an unused area of the OTP ROM.

Change-Id: I518aa4f9408bcaf624278685015d91395fad43f6
Signed-off-by: Caveh Jalali <caveh@google.com>
Reviewed-on: https://chromium-review.googlesource.com/592641