The functions bcmgenet_dma_disable and bcmgenet_enable_dma are
only used as part of dma initialization. Their functionality is
moved inside bcmgenet_init_dma and the functions are removed.
Since the dma is always disabled inside of bcmgenet_init_dma,
the initialization functions bcmgenet_init_rx_queues and
bcmgenet_init_tx_queues no longer need to attempt to manage its
state.
Signed-off-by: Doug Berger <opendmb@xxxxxxxxx>