net: core: cosmetic: A MAC address is not limited to SROM

Currently, we print that the MAC from the SROM does not match. It can be
many forms of ROM, so lets drop the S.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>