ARM: sun5i: gr8: Use common sun5i DTSI

Most of the GR8 DTSI is duplicated with the common sun5i DTSI, and some of
the extra nodes defined there actually apply to all of the sun5i family.

Move those into the common DTSI so that all SoCs can benefit from it, and
include the sun5i DTSI.

Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>