ARM64: dts: meson-gxbb-wetek: add a wetek specific dtsi to cleanup hub and play2

This patch adds a specific wetek dtsi to handle the specific Hub and Play2
boards by no more depending on the p20x dtsi.
This simplifies the hub and play2 dts and will avoid breaking these
boards when adding p200 and p201 specific changes.

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