We see the choice of USB_DWC3_HOST / _GADGET in drivers/usb/dwc3/Kconfig,
but we can not choose USB_DWC3_HOST unless USB_GADGET is defined.
This is strange.
Loosen the "depends on" and also move "select USB_GADGET_DUALSPEED" to
the correct place.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>