netlink: specs: dpll: replace underscores with dashes in names

We're trying to add a strict regexp for the name format in the spec.
Underscores will not be allowed, dashes should be used instead.
This makes no difference to C (codegen, if used, replaces special
chars in names) but it gives more uniform naming in Python.

Fixes: 3badff3a ("dpll: spec: Add Netlink spec in YAML")
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250624211002.3475021-5-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>