tools: ynl-gen: add missing empty line between policies

We're missing empty line between policies.
DPLL will need this.

Tested-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/r/20230808200907.1290647-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -1871,6 +1871,7 @@ def print_req_policy(cw, struct, ri=None):
     for _, arg in struct.member_list():
         arg.attr_policy(cw)
     cw.p("};")
+    cw.nl()
 
 
 def kernel_can_gen_family_struct(family):