fix typo in fs/proc/base.c

Hi Marcelo,

This fixes a typo which got introduced in latest 2.4 bk. Sorry for the attachment. My mailer is currently broken and corrupts diffs.

@@ -780,7 +780,7 @@
 	return inode;
 
 out_unlock:
-	node->u.generic_ip = NULL;
+	inode->u.generic_ip = NULL;
 	iput(inode);
 	return NULL;
 }