ramips: rt305x: add dwc_otg driver

target/linux/ramips/files/arch/mips/ralink/Kconfig

target/linux/ramips/files/drivers/usb/dwc_otg/Kconfig

target/linux/ramips/files/drivers/usb/dwc_otg/Makefile

target/linux/ramips/files/drivers/usb/dwc_otg/dummy_audio.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_attr.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_attr.h

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_cil.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_cil.h

...linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_cil_intr.c

...t/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_driver.c

...t/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_driver.h

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_hcd.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_hcd.h

...linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_hcd_intr.c

...inux/ramips/files/drivers/usb/dwc_otg/dwc_otg_hcd_queue.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_pcd.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_pcd.h

...linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_pcd_intr.c

target/linux/ramips/files/drivers/usb/dwc_otg/dwc_otg_regs.h

...nux/ramips/files/drivers/usb/dwc_otg/linux/dwc_otg_plat.h