[SCSI] fix sg leak when scsi_execute_async fails

Doug found a bug where if scsi_execute_async fails, we are leaking
sg resources. scsi_do_req never failed so we did not have to handle
that case before.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/sg.c

@@ -748,6 +748,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 		/*
 		 * most likely out of mem, but could also be a bad map
 		 */
+		sg_finish_rem_req(srp);
 		return -ENOMEM;
 	} else
 		return 0;