[ARM] pxa/magician: Enable pxa27x_udc and gpio_vbus

This patch depends on otg_transceiver support in pxa27x_udc
(which is queued via linux-usb) to work.
It compiles also without it.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Eric Miao <eric.miao@marvell.com>