ARM64: dts: meson-gx: Prepend GX generic compatible like other nodes

Prepend the compatible strings with a GX generic name in nodes compatible with
the GXBB HW and keep the same scheme as other nodes.

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