pinctrl: uniphier: prohibit drive control for pin 61-66 of PH1-LD11

According to the hardware document, setting the drive control is
prohibited for these pins (N-channel Open Drain pins).  Set their
drive control attribute to "fixed".

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