usb: gadget: r8a66597-udc: add support for SUDMAC

SH7757 has a USB function with internal DMA controller (SUDMAC).
This patch supports the SUDMAC. The SUDMAC is incompatible with
general-purpose DMAC. So, it doesn't use dmaengine.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>