arm: sun8i: h3: drop pinctrl-a10.h inclusion for H3 DTSI

After converting to generic pinconf binding, pinctrl-a10.h is now not
used at all.

Drop its inclusion for H3 DTSI.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>