mptsas: add missing va_end

Reported by Coverity.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/scsi/mptconfig.c b/hw/scsi/mptconfig.c
index d049825..7071854 100644
--- a/hw/scsi/mptconfig.c
+++ b/hw/scsi/mptconfig.c
@@ -123,6 +123,7 @@
         va_copy(ap2, ap1);
         size = vfill(NULL, 0, fmt, ap2);
         *p_data = data = g_malloc(size);
+        va_end(ap2);
     }
     return vfill(data, size, fmt, ap1);
 }