ARM: dts: sun7i: fix typos in uart pin mux

The recently added uart mux options had a few typos.  Fix them.

Fixes: 43d0fe112585 ("ARM: dts: sun7i: add pinctrl for missing uart mux options")
Reported-by: Werner Böllmann <Werner.Boellmann@fh-dortmund.de>
Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>