net: remove smc911x driver

This driver was used on Arm and SH machines until 2009, when the
last platforms moved to the smsc911x driver for the same hardware.

Time to retire this version.

Link: https://lore.kernel.org/netdev/1232010482-3744-1-git-send-email-steve.glendinning@smsc.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20221017121900.3520108-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>