usb: gadget: renesas_usbhs: struct usbhs_pipe hold handler

packet handler had moved to struct usbhs_pipe from struct usbhsg_uep.
it is preparation of mod_host support

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>