usb: renesas_usbhs: fifo became independent from pipe.

Current renesas_usbhs has PIO data transfer mode which controls CFIFO.
And it was implemented in pipe.c.
But, fifo control method needs more flexible implementation
to support DMAEngine.
This patch create fifo.c, and it became independent from pipe.c.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>