IB/core: Initialize ib_device.dev.parent earlier

Move the ib_device.dev.parent initialization code from
ib_device_register_sysfs() to ib_register_device(). Additionally,
allow HBA drivers to set ib_device.dev.parent without setting
ib_device.dma_device. This is the first step towards removing
ib_device.dma_device.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index c1fb545..daadf31 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -1258,7 +1258,7 @@ int ib_device_register_sysfs(struct ib_device *device,
 	int ret;
 	int i;
 
-	device->dev.parent = device->dma_device;
+	WARN_ON_ONCE(!device->dev.parent);
 	ret = dev_set_name(class_dev, "%s", device->name);
 	if (ret)
 		return ret;