netlink: specs: ethtool: 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 replaces special chars in names)
but gives more uniform naming in Python.

Fixes: 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")
Fixes: 46fb3ba95b93 ("ethtool: Add an interface for flashing transceiver modules' firmware")
Reviewed-by: Kory Maincent <[e-mail]>
Reviewed-by: Donald Hunter <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/ethtool.yaml

···
         name: started
         doc: The firmware flashing process has started.
       -
-        name: in_progress
+        name: in-progress
         doc: The firmware flashing process is in progress.
       -
         name: completed
···
         name: hkey
         type: binary
       -
-        name: input_xfrm
+        name: input-xfrm
         type: u32
       -
         name: start-context
···
             - hfunc
             - indir
             - hkey
-            - input_xfrm
+            - input-xfrm
       dump:
         request:
           attributes:

tools/testing/selftests/drivers/net/hw/rss_input_xfrm.py

···
         raise KsftSkipEx("socket.SO_INCOMING_CPU was added in Python 3.11")
 
     input_xfrm = cfg.ethnl.rss_get(
-        {'header': {'dev-name': cfg.ifname}}).get('input_xfrm')
+        {'header': {'dev-name': cfg.ifname}}).get('input-xfrm')
 
     # Check for symmetric xor/or-xor
     if not input_xfrm or (input_xfrm != 1 and input_xfrm != 2):