pinctrl: uniphier: support UniPhier PH1-LD11 pinctrl driver

The pinmux of PH1-LD11 is almost a subset of that of PH1-LD20
(as far as used in boot-loader), so this commit makes the driver
shared between the two SoCs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>