rtnetlink: Remove "net" from newlink params

Now that devices have been converted to use the specific netns instead
of ambiguous "net", let's remove it from newlink parameters.

Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250219125039.18024-11-shaw.leon@gmail.com


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