pinctrl: renesas: r8a7792: Share QSPI pin group data

Pin group qspi_data2 is a subset of qspi_data4.

This reduces kernel size by 16 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/7887faaeed7bb0d6f06977aa0ef2873f74528bf0.1640269757.git.geert+renesas@glider.be