soc: mediatek: mtk-socinfo Add error handling in devm_kasprintf()

Add an error check to the devm_kasprintf() function in
mtk_socinfo_create_socinfo_node(), returning -ENOMEM if the function
failed.

Assisted-by: gkh_clanker_t1000
CC: Matthias Brugger <matthias.bgg@gmail.com>
CC: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>