mptsas: fix memory leak

Reported by Coverity.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/scsi/mptsas.c

@@ -504,6 +504,7 @@ reply_maybe_async:
             reply_async->IOCLogInfo = count;
             return;
         }
+        g_free(reply_async);
         reply.TerminationCount = count;
         break;