switch xattr_handler->set() to passing dentry and inode separately

preparation for similar switch in ->setxattr() (see the next commit for
rationale).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/xattr_security.c b/fs/ext4/xattr_security.c
index 123a7d0..a892111 100644
--- a/fs/ext4/xattr_security.c
+++ b/fs/ext4/xattr_security.c
@@ -22,10 +22,11 @@
 
 static int
 ext4_xattr_security_set(const struct xattr_handler *handler,
-			struct dentry *dentry, const char *name,
-			const void *value, size_t size, int flags)
+			struct dentry *unused, struct inode *inode,
+			const char *name, const void *value,
+			size_t size, int flags)
 {
-	return ext4_xattr_set(d_inode(dentry), EXT4_XATTR_INDEX_SECURITY,
+	return ext4_xattr_set(inode, EXT4_XATTR_INDEX_SECURITY,
 			      name, value, size, flags);
 }