arm64: dts: meson-s4-aq222: update compatible string with s805x2

arm64: dts: meson-s4-aq222: update compatible string with s805x2

Update the compatible string for the Amlogic AQ222 board to include
the specific SoC compatible "amlogic,s805x2".

This aligns the device tree with the updated bindings which now
differentiate between S4 family members (S805X2 vs S905Y4).

Signed-off-by: Nick Xie <nick@khadas.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260115030015.1334517-3-nick@khadas.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>