tools: ynl-gen: switch to family struct

We'll want to store static info about the family soon.
Generate a struct. This changes creation from, e.g.:

	 ys = ynl_sock_create("netdev", &yerr);
to:
	 ys = ynl_sock_create(&ynl_netdev_family, &yerr);

on user's side.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -2109,6 +2109,16 @@ def render_uapi(family, cw):
     cw.p(f'#endif /* {hdr_prot} */')
 
 
+def render_user_family(family, cw, prototype):
+    symbol = f'const struct ynl_family ynl_{family.c_name}_family'
+    if prototype:
+        cw.p(f'extern {symbol};')
+    else:
+        cw.block_start(f'{symbol} = ')
+        cw.p(f'.name = "{family.name}",')
+        cw.block_end(line=';')
+
+
 def find_kernel_root(full_path):
     sub_path = ''
     while True:
@@ -2205,6 +2215,8 @@ def main():
         else:
             cw.p('struct ynl_sock;')
             cw.nl()
+            render_user_family(parsed, cw, True)
+        cw.nl()
 
     if args.mode == "kernel":
         if args.header:
@@ -2397,6 +2409,9 @@ def main():
                 cw.p('/* --------------- Common notification parsing --------------- */')
                 print_ntf_type_parse(parsed, cw, args.mode)
 
+            cw.nl()
+            render_user_family(parsed, cw, False)
+
     if args.header:
         cw.p(f'#endif /* {hdr_prot} */')