tools/net/ynl: Fix c codegen for array-nest

ynl-gen-c generates e.g. 'calloc(mcast_groups, sizeof(*dst->mcast_groups))'
for array-nest attrs when it should be 'n_mcast_groups'.

Add a 'n_' prefix in the generated code for array-nests.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20240306231046.97158-4-donald.hunter@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/ynl-gen-c.py

@@ -1667,7 +1667,7 @@ def _multi_parse(ri, struct, init_lines, local_vars):
         aspec = struct[anest]
 
         ri.cw.block_start(line=f"if (n_{aspec.c_name})")
-        ri.cw.p(f"dst->{aspec.c_name} = calloc({aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
+        ri.cw.p(f"dst->{aspec.c_name} = calloc(n_{aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
         ri.cw.p(f"dst->n_{aspec.c_name} = n_{aspec.c_name};")
         ri.cw.p('i = 0;')
         ri.cw.p(f"parg.rsp_policy = &{aspec.nested_render_name}_nest;")