The mtk-socinfo driver uses symbols 'soc_device_register' and
'soc_device_unregister' which are part of the bus driver for
System-on-Chip devices.

Select SOC_BUS to make sure that driver is built and the symbols are
available.

Fixes: 423a54da ("soc: mediatek: mtk-socinfo: Add driver for getting chip information")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/cc8f7f7da5bdccce514a320e0ae7468659cf7346.1707327680.git.daniel@makrotopia.orgSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>