usbc: Allow setting CONFIG_USB_PD_TCPC_LOW_POWER=n
usbc: Allow setting CONFIG_USB_PD_TCPC_LOW_POWER=n

By default, CONFIG_USB_PD_TCPC_LOW_POWER is enabled, and if it is
set to 'n', there are compile errors.
Allow setting the config to disable low power mode.

BUG=b:214883916
TEST=zmake configure -b nissa; flash and run
BRANCH=none

Signed-off-by: Andrew McRae <44ad1424cfc8411c96d9181798ca41ae55709dfb@google.com>
Change-Id: I217645e6b169550efc075cd06a2fa62aa440e197
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3392105
Reviewed-by: Peter Marheine <ef0b2c492edde94778d7465bfbaeed52c5be6858@chromium.org>
Commit-Queue: Peter Marheine <ef0b2c492edde94778d7465bfbaeed52c5be6858@chromium.org>

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