Add console and usb_spi commands to enable or disable IOs
to the socket, so that it will not be powered if a chip is inserted,
and control reset and boot_cfg.
BUG=b:36910757
BRANCH=None
TEST=Check no voltage when socket is disabled. Full spiflash compatibility.
Change-Id: Ie4ce0613a868030833abfdccd827acce2753dc6f
Reviewed-on: https://chromium-review.googlesource.com/509072
Commit-Ready: Nick Sanders <nsanders@chromium.org>
Tested-by: Nick Sanders <nsanders@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>