dt-bindings: fix for Allwinner H5 pinctrl's compatible

The compatible for Allwinner H5 pin controller is wrong written as
allwinner,sun50i-h5-r-pinctrl, however, it's really a generic pinctrl
rather than a "r" one.

Fix this compatible string.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>