Allow any data type in primary expression

There are a few system functions that take either an expression or a data
type. This is implemented in the parser by allowing a type identifier as a
primary expression.

But those functions allow any data type, not just typedefs. E.g.

```
$bits(int);
$bits(reg [1:0]);
$bits(struct packed { int x; });
```

Support this by changing the parser rule from TYPE_IDENTIFIER to data_type.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

parse.y

@@ -3760,12 +3760,10 @@ expr_primary_or_typename
 
   /* There are a few special cases (notably $bits argument) where the
      expression may be a type name. Let the elaborator sort this out. */
-  | TYPE_IDENTIFIER
-      { pform_set_type_referenced(@1, $1.text);
-	PETypename*tmp = new PETypename($1.type);
-	FILE_NAME(tmp,@1);
+  | data_type
+      { PETypename*tmp = new PETypename($1);
+	FILE_NAME(tmp, @1);
 	$$ = tmp;
-	delete[]$1.text;
       }
 
   ;