ARM: sunxi: Restructure sunxi dts/dtsi files

For the new sun4i/Cubieboard (A10) support, lets re-strucure the
sun5i dts files to make it more generic. Those are the new
dts/dtsi files:

sunxi.dtsi - Devices common to all Allwinner sunXi SoC's
sun4i.dtsi - sun4i Devices, will include sunxi.dtsi
sun5i.dtsi - sun5i Devices, will include sunxi.dtsi
board.dts - will include either sun4i.dtsi or sun5i.dtsi

Additionally the "duart" label in the olinuxino.dts is changed to
"uart1".

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>