dmaengine: idxd: add engine 'struct device' missing bus type assignment

engine 'struct device' setup is missing assigning the bus type. Add it to
dsa_bus_type.

Fixes: 75b9113090 ("dmaengine: idxd: fix engine conf_dev lifetime")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/161947841562.984844.17505646725993659651.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/idxd/init.c

@@ -242,6 +242,7 @@ static int idxd_setup_engines(struct idxd_device *idxd)
 		engine->idxd = idxd;
 		device_initialize(&engine->conf_dev);
 		engine->conf_dev.parent = &idxd->conf_dev;
+		engine->conf_dev.bus = &dsa_bus_type;
 		engine->conf_dev.type = &idxd_engine_device_type;
 		rc = dev_set_name(&engine->conf_dev, "engine%d.%d", idxd->id, engine->id);
 		if (rc < 0) {