Fix returning of old info callback

Thanks to Sreerenj Balachandran <sreerenj.balachandran@intel.com> for
noticing this error.

Signed-off-by: Mark Thompson <sw@jkqxz.net>
diff --git a/va/va.c b/va/va.c
index ffc0e31..38a618a 100644
--- a/va/va.c
+++ b/va/va.c
@@ -177,7 +177,7 @@
         return NULL;
 
     dctx = (VADisplayContextP)dpy;
-    old_callback = dctx->error_callback;
+    old_callback = dctx->info_callback;
 
     dctx->info_callback = callback;
     dctx->info_callback_user_context = user_context;