pinctrl: renesas: r8a779f0: Remove unused POC2

The POWER Condition Control Register 2 (POC2) is unused, and the
documentation does not define any valid bits.  Remove it.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/d8a9ea39b49d24e39f4da3f00b64bce34016887d.1655301529.git.geert+renesas@glider.be