ARM: dts: meson: organize devices in their corresponding busses

The Amlogic Meson SoCs have most of the internal peripherals organized
in busses. Use them to make the dts easier to read and to avoid
duplicated register (bus) offset definitions.

The bus information is taken from the vendor kernel:
	#define IO_CBUS_PHY_BASE        0xc1100000  ///2M
	#define IO_AOBUS_PHY_BASE       0xc8100000  ///1M

There are more internal busses (such as the abp bus which seems to
contain audio, HDMI and Mali registers), but since we don't have
drivers for them yet these are not added (yet).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
[khilman: minor whitespace fix]
Signed-off-by: Kevin Hilman <khilman@baylibre.com>