NFSv4: Allow tracing of NFSv4 fsync calls

I appear to have missed this when adding the ftrace probes.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfstrace.c b/fs/nfs/nfstrace.c
index 4eb0aea..c74f7af 100644
--- a/fs/nfs/nfstrace.c
+++ b/fs/nfs/nfstrace.c
@@ -7,3 +7,6 @@
 
 #define CREATE_TRACE_POINTS
 #include "nfstrace.h"
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs_fsync_enter);
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs_fsync_exit);