net: bcmgenet: code movement

The Hardware Filter Block code will be used by ethtool functions
when defining flow types so this commit moves the functions in the
file to prevent the need for prototype declarations.

This is broken out to facilitate review.

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