Pbody: add override for JTAG to UART for USBPD

Enable access to USBPD on Pbody boards.

BUG=chrome-os-partner:56978
TEST=1. Run 'cros_workon --host start hdctools'
            'sudo emerge hdctools'
            'sudo servod --board pbody'
     2. Then see if PD MCU UART is served successfully.

Change-Id: I33afbb9c034758ef5ab939836d0a0486eefd5a43
Signed-off-by: Kaiyen Chang <kaiyen.chang@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/400140
Reviewed-by: Shawn N <shawnn@chromium.org>
(cherry picked from commit 73133d7ec284ad09370b2301328294a873306d1b)
Reviewed-on: https://chromium-review.googlesource.com/401067
1 file changed