netlink: specs: devlink: 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: 429ac621 ("devlink: define enum for attr types of dynamic attributes")
Fixes: f2f9dd16 ("netlink: specs: devlink: add the remaining command to generate complete split_ops")
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250624211002.3475021-6-kuba@kernel.org


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