net: bcmgenet: remove meaningless lines

An assortment of non-functional lines are removed to reduce confusion
and some typos in comments are corrected.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>