Merge branch 'net-ethernet-renesas-infrastructure-preparations-for-upcoming-driver'

Wolfram Sang says:

====================
net: ethernet: renesas: infrastructure preparations for upcoming driver

Before we upstream a new driver, Niklas and I thought that a few
cleanups for Kconfig/Makefile will help readability and maintainability.
Here they are, looking forward to comments.
====================

Link: https://lore.kernel.org/r/20231022205316.3209-1-wsa+renesas@sang-engineering.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>