usb: pch_udc: Fix compile error, warnings and checkpatch warnings

Building pch_udc in linux-next fails, this patch fixes the a compile
error:

drivers/usb/gadget/pch_udc.c: In function ‘usb_gadget_register_driver’:
drivers/usb/gadget/pch_udc.c:2645: error: ‘struct usb_gadget_driver’ has no member named ‘bind’
drivers/usb/gadget/pch_udc.c:2664: error: ‘struct usb_gadget_driver’ has no member named ‘bind’

And a couple of compiler warnings and checkpatch warnings.

Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>