[SCSI] fix duplicate removal on error path in scsi_sysfs_add_sdev

This patch (as1335) fixes a bug in scsi_sysfs_add_sdev().  Its callers
always remove the device if anything goes wrong, so it should never
remove the device.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>