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>