scripts: coccinelle: devm_free: reduce false positives

False positives could be introduced due to allocations using the new
_obj functions.  Add these to the "safe" rule accordingly.

False positives could also be introduced when the same variable
name has two possible types.  Incorporate type information to avoid
reporting this case  This does lead to false negatives when no type
information is available.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reported-by: Ricardo Ribalda <ribalda@chromium.org>

scripts/coccinelle/free/devm_free.cocci

@@ -26,7 +26,8 @@ virtual report
 virtual context
 
 @r depends on context || org || report@
-expression x;
+type T;
+T x;
 @@
 
 (
@@ -56,18 +57,26 @@ expression x;
 )
 
 @safe depends on context || org || report exists@
-expression x;
+r.T x;
 position p;
 @@
 
 (
  x = kmalloc(...)
+|
+ x = kmalloc_obj(...)
+|
+ x = kmalloc_objs(...)
 |
  x = kvasprintf(...)
 |
  x = kasprintf(...)
 |
  x = kzalloc(...)
+|
+ x = kzalloc_obj(...)
+|
+ x = kzalloc_objs(...)
 |
  x = kmalloc_array(...)
 |
@@ -105,7 +114,7 @@ position p;
 )
 
 @pb@
-expression r.x;
+r.T r.x;
 position p != safe.p;
 @@