USB: Fix trout build failure with ci13xxx_msm gadget

This patch fixes the below compilation errors.

  CC      drivers/usb/gadget/ci13xxx_msm.o
  CC      net/mac80211/led.o
  drivers/usb/gadget/ci13xxx_msm.c: In function 'ci13xxx_msm_notify_event':
  drivers/usb/gadget/ci13xxx_msm.c:42: error: 'USB_AHBBURST' undeclared (first use in this function)
  drivers/usb/gadget/ci13xxx_msm.c:42: error: (Each undeclared identifier is reported only once
  drivers/usb/gadget/ci13xxx_msm.c:42: error: for each function it appears in.)
  drivers/usb/gadget/ci13xxx_msm.c:43: error: 'USB_AHBMODE' undeclared (first use in this function)
make[4]: *** [drivers/usb/gadget/ci13xxx_msm.o] Error 1
make[3]: *** [drivers/usb/gadget] Error 2

MSM USB driver is not supported on boards like trout (MSM7201) which
has an external PHY.

Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>