skeleton.dtsi is deprecated. Remove it from sun8i-a83t.dtsi and add
the needed device nodes directly.

Also drop an extra, non-style-conforming line in the copyright license
header.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>