fuse: use atomic64_t for khctr

...to get rid of one more fc->lock use.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b1ac587..033e30a 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -544,7 +544,7 @@ struct fuse_conn {
 	struct fuse_iqueue iq;
 
 	/** The next unique kernel file handle */
-	u64 khctr;
+	atomic64_t khctr;
 
 	/** rbtree of fuse_files waiting for poll events indexed by ph */
 	struct rb_root polled_files;