drivers/built-in.o: In function `pxa25x_udc_probe':
drivers/usb/gadget/pxa25x_udc.c:2195: undefined reference to `otg_get_transceiver'
drivers/usb/gadget/pxa25x_udc.c:2300: undefined reference to `otg_put_transceiver'

pxa25x_udc.c unconditionally uses these two functions, so we need to
ensure that the object providing them is also built.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>