net: ethtool: call .parse_request for SET handlers

In preparation for using req_info to carry parameters between SET
and NTF - call .parse_request during ethnl_default_set_doit().

The main question here is whether .parse_request is intended to be
GET-specific. Originally the SET handling was delegated to each subcommand
directly - ethnl_default_set_doit() and .set callbacks in ethnl_request_ops
did not exist. Looking at existing users does not shed much light, all
of the following subcommands use .parse_request but have no SET handler
(and no NTF):

  net/ethtool/eeprom.c
  net/ethtool/rss.c
  net/ethtool/stats.c
  net/ethtool/strset.c
  net/ethtool/tsinfo.c

There's only one which does have a SET:

  net/ethtool/pause.c

where .parse_request handling is used to select which statistics to query.
Not relevant for SET but also harmless.

Going back to RSS (which doesn't have SET today) .parse_request parses
the rss_context ID. Using the req_info struct to pass the context ID
from SET to NTF will be very useful.

Switch to ethnl_default_parse(), effectively adding the .parse_request
for SET handlers.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20250623231720.3124717-4-kuba@kernel.org


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