This patch adds support for NLA_POLICY_NESTED_ARRAY() policies.

Example spec (from future wireguard.yaml):
-
  name: wgpeer
  attributes:
    -
      name: allowedips
      type: indexed-array
      sub-type: nest
      nested-attributes: wgallowedip

yields NLA_POLICY_NESTED_ARRAY(wireguard_wgallowedip_nl_policy).

This doesn't change any currently generated code, as it isn't
used in any specs currently used for generating code.

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/net/ynl/pyynl/ynl_gen_c.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index 1543d4911bf5..b7de7f6b1fc7 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -816,6 +816,11 @@ class TypeArrayNest(Type):
                     f'unsigned int n_{self.c_name}']
         return super().arg_member(ri)
 
+    def _attr_policy(self, policy):
+        if self.attr['sub-type'] == 'nest':
+            return f'NLA_POLICY_NESTED_ARRAY({self.nested_render_name}_nl_policy)'
+        return super()._attr_policy(policy)
+
     def _attr_typol(self):
         if self.attr['sub-type'] in scalars:
             return f'.type = YNL_PT_U{c_upper(self.sub_type[1:])}, '
-- 
2.51.0