pinctrl: renesas: r8a7796: Share QSPI pin group data

Pin groups qspi[01]_data2 are subsets of qspi[01]_data4.

This reduces kernel size by 32 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/602b718b26d5a61b59bfca785f804f0c4a8e09bc.1640269757.git.geert+renesas@glider.be