net: bcmgenet: always enable status blocks

The hardware offloading of the NETIF_F_HW_CSUM and NETIF_F_RXCSUM
features requires the use of Transmit Status Blocks before transmit
frame data and Receive Status Blocks before receive frame data to
carry the checksum information.

Unfortunately, these status blocks are currently only enabled when
the NETIF_F_HW_CSUM feature is enabled. As a result NETIF_F_RXCSUM
will not actually be offloaded to the hardware unless both it and
NETIF_F_HW_CSUM are enabled. Fortunately, that is the default
configuration.

This commit addresses this issue by always enabling the use of
status blocks on both transmit and receive frames. Further, it
replaces the use of a dedicated flag within the driver private
data structure with direct use of the netdev features flags.

Fixes: 81015539 ("net: bcmgenet: use CHECKSUM_COMPLETE for NETIF_F_RXCSUM")
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>