tools: ynl: call nested attribute free function for indexed arrays

When freeing indexed arrays, the corresponding free function should
be called for each entry of the indexed array. For example, for
for 'struct tc_act_attrs' 'tc_act_attrs_free(...)' needs to be called
for each entry.

Previously, memory leaks were reported when enabling the ASAN
analyzer.

=================================================================
==874==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7f221fd20cb5 in malloc ./debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:67
#1 0x55c98db048af in tc_act_attrs_set_options_vlan_parms ../generated/tc-user.h:2813
#2 0x55c98db048af in main ./linux/tools/net/ynl/samples/tc-filter-add.c:71

Direct leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7f221fd20cb5 in malloc ./debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:67
#1 0x55c98db04a93 in tc_act_attrs_set_options_vlan_parms ../generated/tc-user.h:2813
#2 0x55c98db04a93 in main ./linux/tools/net/ynl/samples/tc-filter-add.c:74

Direct leak of 10 byte(s) in 2 object(s) allocated from:
#0 0x7f221fd20cb5 in malloc ./debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:67
#1 0x55c98db0527d in tc_act_attrs_set_kind ../generated/tc-user.h:1622

SUMMARY: AddressSanitizer: 58 byte(s) leaked in 4 allocation(s).

The following diff illustrates the changes introduced compared to the
previous version of the code.

void tc_flower_attrs_free(struct tc_flower_attrs *obj)
{
+ unsigned int i;
+
free(obj->indev);
+ for (i = 0; i < obj->_count.act; i++)
+ tc_act_attrs_free(&obj->act[i]);
free(obj->act);
free(obj->key_eth_dst);
free(obj->key_eth_dst_mask);

Signed-off-by: Zahari Doychev <[e-mail]>
Reviewed-by: Jakub Kicinski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/net/ynl/pyynl/ynl_gen_c.py

···
         return [f"{member} = {self.c_name};",
                 f"{presence} = n_{self.c_name};"]
 
+    def free_needs_iter(self):
+        return self.sub_type == 'nest'
+
+    def _free_lines(self, ri, var, ref):
+        lines = []
+        if self.sub_type == 'nest':
+            lines += [
+                f"for (i = 0; i < {var}->{ref}_count.{self.c_name}; i++)",
+                f'{self.nested_render_name}_free(&{var}->{ref}{self.c_name}[i]);',
+            ]
+        lines += f"free({var}->{ref}{self.c_name});",
+        return lines
 
 class TypeNestTypeValue(Type):
     def _complex_member_type(self, ri):