usb: renesas_usbhs: fix the usb_pkt_pop()

This patch fixes the usb_pkt_pop(). If a gadget driver calls
usb_ep_dequeue(), this driver will call the usb_pkt_pop().
So, the usb_pkt_pop() should cancel the transaction.

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