soc: amlogic: meson-gx-socinfo: use new soc_device_register functionality to populate machine name

A new fallback mechanism has been added to soc_device_register that
populates machine with the DT model information if machine isn't set yet.
This allows to remove this code here.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/ac3b4356-d4c3-25e4-9bc2-c5b369c676b2@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>