usb: renesas_usbhs: modify data transfer interrupt

On current driver, overall data transfer method was implemented in fifo.c,
but its interrupt which is member of packet queue control
was still in mod_gadget.c.
This patch move it into fifo.c.
By this patch, the packet/fifo control is independent from mod_gadget.

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