volteer: Enable PLATFORM_EC_USB_PD_ALT_MODE_UFP

This is needed to enable the power-delivery task since the option is not
enabled by default.

BUG=b:175434113
TEST=make BOARD=volteer -j30
build volteer on zephyr

Signed-off-by: Simon Glass <sjg@chromium.org>
Cq-Depend: chromium:2617204
Change-Id: I3f3c9c76828cc3bef3303126c7c42f052c954a4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/zephyr-chrome/+/2623427
Reviewed-by: Keith Short <keithshort@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
1 file changed