pinctrl: uniphier: drop meaningless pin from SD1 pin-mux of Pro4

The pin 327 was supposed to be used as a voltage control line for the
SD card regulator, but the SD card port1 does not support UHS-I.  It
only supports 3.3V signaling, hence this pin is pointless.

Just a note about the background.  At first, hardware engineers tried
to implement the UHS for this port.  Then, they needed to shrink the
silicon die size, and gave up the UHS, but forgot to remove the pin
assignment.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>