net: ethtool: remove duplicate defines for family info

Commit under fixes switched to uAPI generation from the YAML
spec. A number of custom defines were left behind, mostly
for commands very hard to express in YAML spec.

Among what was left behind was the name and version of
the generic netlink family. Problem is that the codegen
always outputs those values so we ended up with a duplicated,
differently named set of defines.

Provide naming info in YAML and remove the incorrect defines.

Fixes: 8d0580c6eb ("ethtool: regenerate uapi header from the spec")
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250617202240.811179-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/ethtool.yaml

@@ -7,6 +7,9 @@ protocol: genetlink-legacy
 doc: Partial family for Ethtool Netlink.
 uapi-header: linux/ethtool_netlink_generated.h
 
+c-family-name: ethtool-genl-name
+c-version-name: ethtool-genl-version
+
 definitions:
   -
     name: udp-tunnel-type