ubifs: introduce Kconfig symbol for xattr support

Allow to disable extended attribute support.

This aids in reliability testing, especially since some xattr
related bugs have surfaced.

Also an embedded system might not need it, so this allows for a
slightly smaller kernel (about 4KiB).

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 54fb6b1..8293086 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1755,7 +1755,13 @@ int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
 		    size_t size, int flags, bool check_lock);
 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
 			size_t size);
+
+#ifdef CONFIG_UBIFS_FS_XATTR
 void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum);
+#else
+static inline void ubifs_evict_xattr_inode(struct ubifs_info *c,
+					   ino_t xattr_inum) { }
+#endif
 
 #ifdef CONFIG_UBIFS_FS_SECURITY
 extern int ubifs_init_security(struct inode *dentry, struct inode *inode,