Fix T41744: Hidden keymap properties uneditable

For UI & operator toolbar this makes sense,
but for keymaps - hidden props can make an important difference.

source/blender/editors/interface/interface_templates.c

@@ -3495,13 +3495,9 @@ static void template_keymap_item_properties(uiLayout *layout, const char *title,
 
 	RNA_STRUCT_BEGIN (ptr, prop)
 	{
-		int flag = RNA_property_flag(prop);
 		const bool is_set = RNA_property_is_set(ptr, prop);
 		uiBut *but;
 
-		if (flag & PROP_HIDDEN)
-			continue;
-
 		/* recurse for nested properties */
 		if (RNA_property_type(prop) == PROP_POINTER) {
 			PointerRNA propptr = RNA_property_pointer_get(ptr, prop);