ARM64: dts: meson-gxbb: Move common nodes to meson-gx

Move common nodes between GXBB and GXL in to the common GX dtsi.
Leave the clock attributes in the GXBB dtsi for now.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>