HACK: usb: gadget: Fix enumeration on boot

The Android gadget driver disconnects the gadget on bind
and expects the gadget to stay disconnected until it calls
usb_gadget_connect when userspace is ready. Removed the call
to usb_gadget_connect in usb_gadget_probe_driver to avoid
enabling the pullup before userspace is ready.

Change-Id: I63707ac6e16a44eca52351a4bf80407d25fbd35e
Signed-off-by: Benoit Goby <benoit@android.com>