usb: gadget: udc: renesas_usb3: Fix PN_INT_ENA disabling timing

The PN_INT_ENA register should be used after usb3_pn_change() is called.
So, this patch moves the access from renesas_usb3_stop_controller() to
usb3_disable_pipe_n().

Fixes: 746bfe63

 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>