ARM: dts: meson: group the Cortex-A5 / Cortex-A9 peripherals

The public Meson8b (S805) datasheet describes a memory region called "A9
Periph base" which starts at 0xC4300000 and ends at 0xC430FFFF. Add a
simple-bus node and move all peripherals that are part of this memory
region.
This makes the .dts a bit easier to read. No functional changes.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>