usb: gadget: udc: renesas_usb3: disable the controller's irqs for reconnecting

This patch fixes an issue that reconnection is possible to fail
because unexpected state handling happens by the irqs. To fix the issue,
the driver disables the controller's irqs when disconnected.

Fixes: 746bfe63 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
Cc: <stable@vger.kernel.org> # v4.5+
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>