ARM64: dts: meson-gxl-s905x-libretech-cc: fixup board definition

The libretech CC derives less from the p212 than initially thought.
Several voltage regulators are different and the capabilities of the
sdcard and emmc also differ.

Deriving from the p212 is not convient anymore so the libretech is now
derived from s905x definition directly.

Fixes: cd84aff1 ("ARM64: dts: meson-gxl: Add Libre Technology CC support")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>