arm64: dts: meson: bananapi-m5: convert dts to dtsi

Convert the BPI-M5 dts into meson-sm1-bananapi.dtsi to support the
addition of new boards based on the same design.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230127142221.3718184-4-christianshewitt@gmail.com


[narmstrong: fixed adc-keys node name]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>