Pin group cf_data8 is a subset of cf_data16.

This reduces kernel size by 64 bytes.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/370d823be136cc9ead7051915a1454252a57efc4.1640269757.git.geert+renesas@glider.be