sh-pfc: r8a7779: Don't group USB OVC and PENC pins

The USB_OVCn pins are alternate options for USB over-current detection
when using a 3.3V USB interface. As they're not mandatory they can be
used independently of the USB PENC pins. Don't group the USB_OVCn and
PENC pins to avoid conflicts when the USB_OVCn pins are used by another
function.

Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>