coccinelle: ifnullfree: various cleanups

Adjust tests to compare against NULL, to match cases that explicitly make
that comparison.

Remove removal and re-addition of freeing functions.

Add position variable on usb_free_urb in the non-patch case.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/free/ifnullfree.cocci

@@ -16,28 +16,24 @@ virtual context
 @r2 depends on patch@
 expression E;
 @@
-- if (E)
+- if (E != NULL)
 (
--	kfree(E);
-+ kfree(E);
+  kfree(E);
 |
--	debugfs_remove(E);
-+ debugfs_remove(E);
+  debugfs_remove(E);
 |
--	debugfs_remove_recursive(E);
-+ debugfs_remove_recursive(E);
+  debugfs_remove_recursive(E);
 |
--	usb_free_urb(E);
-+ usb_free_urb(E);
+  usb_free_urb(E);
 )
 
 @r depends on context || report || org @
 expression E;
 position p;
 @@
 
-* if (E)
-*	\(kfree@p\|debugfs_remove@p\|debugfs_remove_recursive@p\|usb_free_urb\)(E);
+* if (E != NULL)
+*	\(kfree@p\|debugfs_remove@p\|debugfs_remove_recursive@p\|usb_free_urb@p\)(E);
 
 @script:python depends on org@
 p << r.p;