net: ibm: emac: use devm for alloc_etherdev

Allows to simplify the code slightly. This is safe to do as free_netdev
gets called last.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240912024903.6201-2-rosenp@gmail.com


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