pinctrl: renesas: r8a7740: Share MMC pin group data

Pin groups mmc0_data[14]_[01] are subsets of mmc0_data8_[01].

This reduces kernel size by 80 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/4b15d28bb8ac24417be83b1defe0bbb908abc1e6.1640269757.git.geert+renesas@glider.be