ARM: dts: sun8i: h2-plus: remove unnecessary mmc1_pins node

The mmc1_pins node with bias-pull-up attribute is already defined in
the sunxi-h3-h5.dtsi file. Thus, we can remove it from here.

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>