add missing free sgtable in scsi_init_io error path

I was testing different errors while running multipath, and becuase of a bug in dm-multiapth I hit the "Incorrect number of segments after building list" error. The attached patch just adds a missing scsi_release_buffers() at the bottom of the scsi_init_io where the table was allocated successfully, but you can return BLKPREP_KILL when someone messes up segment counts.

Mike Christie

@@ -917,6 +917,7 @@ static int scsi_init_io(struct scsi_cmnd
 			req->current_nr_sectors);
 
 	/* release the command and kill it */
+	scsi_release_buffers(cmd);
 	scsi_put_command(cmd);
 	return BLKPREP_KILL;
 }