Staging: hv: Fix null pointer error after vmbus loading

Fix null pointer error after vmbus loading. Remove code that checks for
dev_name, the affected structure is kzalloc-ed prior to this routine, so
it is always null at this stage.

Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>