usb: renesas_usbhs: add the channel number in dma-names

To connect the channel of USB-DMAC to USBHS DnFIFO number, this patch
adds this channel/FIFO number in dma-names. Otherwise, this driver
needs to add analysis code for device tree.

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