usb: dwc3: Fix compilation break when building with USB_DWC3_DUAL_ROLE=y

The commit:
388e5c51 usb: dwc3: remove dwc3 dependency on host AND gadget
breaks compilation when
USB=y, USB_GADGET=m, USB_DWC3=y and USB_DWC3_DUAL_ROLE=y.

drivers/built-in.o: In function `dwc3_gadget_giveback':
drivers/usb/dwc3/gadget.c:271: undefined reference to `usb_gadget_unmap_request'
drivers/built-in.o: In function `__dwc3_gadget_kick_transfer':
drivers/usb/dwc3/gadget.c:1005: undefined reference to `usb_gadget_unmap_request'
drivers/built-in.o: In function `__dwc3_gadget_ep_queue':
drivers/usb/dwc3/gadget.c:1073: undefined reference to `usb_gadget_map_request'
drivers/built-in.o: In function `dwc3_gadget_reset_interrupt':
drivers/usb/dwc3/gadget.c:2165: undefined reference to `usb_gadget_set_state'
drivers/built-in.o: In function `dwc3_gadget_init':
drivers/usb/dwc3/gadget.c:2647: undefined reference to `usb_add_gadget_udc'
drivers/built-in.o: In function `dwc3_gadget_exit':
drivers/usb/dwc3/gadget.c:2681: undefined reference to `usb_del_gadget_udc'
drivers/built-in.o: In function `__dwc3_ep0_do_control_data':
drivers/usb/dwc3/ep0.c:929: undefined reference to `usb_gadget_map_request'
drivers/usb/dwc3/ep0.c:906: undefined reference to `usb_gadget_map_request'
drivers/built-in.o: In function `dwc3_ep0_set_config':
drivers/usb/dwc3/ep0.c:575: undefined reference to `usb_gadget_set_state'
drivers/built-in.o: In function `dwc3_ep0_set_address':
drivers/usb/dwc3/ep0.c:520: undefined reference to `usb_gadget_set_state'
drivers/usb/dwc3/ep0.c:522: undefined reference to `usb_gadget_set_state'
drivers/built-in.o: In function `dwc3_ep0_set_config':
drivers/usb/dwc3/ep0.c:556: undefined reference to `usb_gadget_set_state'

Making changes similar to patch:
71a5e61b usb: chipidea: fix and improve dependencies if usb host or gadget support is built as module

Let us limit the DWC3 mode to depend on corresponding usb-subsystem
and USB_DWC3.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>