arm64: dts: allwinner: a64: Fix display pipeline endpoints

Commit a7f7047f ("arm64: dts: allwinner: a64: Add cross links for the
mixers") introduced a few errors while fixing the cross links. Make sure to
correct them.

Fixes: a7f7047f ("arm64: dts: allwinner: a64: Add cross links for the mixers")
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>