pinctrl: renesas: r8a7790: Share USB1 pin group data

Pin group usb0_ovc_vbus is a subset of usb0.
Pin group usb1_pwen is a subset of usb1.

This reduces kernel size by 16 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/b9f37cf00064293b4b6f9068bda8c1ab819090f5.1640269757.git.geert+renesas@glider.be