debugfs: provide debugfs_create_x64() when disabled

commit 15b0beaa33 ("Add x64 support to debugfs") added
debugfs_create_x64(), but forgot to provide it when debugfs is
disabled, causing problems when code tries to use it even then.
Provide the appropriate static inline.

Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/debugfs.h

@@ -192,6 +192,13 @@ static inline struct dentry *debugfs_create_x32(const char *name, umode_t mode,
 	return ERR_PTR(-ENODEV);
 }
 
+static inline struct dentry *debugfs_create_x64(const char *name, umode_t mode,
+						struct dentry *parent,
+						u64 *value)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
 				     struct dentry *parent,
 				     size_t *value)