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/5bf6a5bd35e619c5d5da4a49878a88f48bb62a30.1640269757.git.geert+renesas@glider.be