arm/mach-meson: move smc commands in cmd/meson

It is incorrect to keep commands in the arch/ folder.

Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230110105650.54580-3-avromanov@sberdevices.ru


[narmstrong: moved after cmd/sound in index.rst]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>