net: bcmgenet: Utilize correct struct device for all DMA operations

__bcmgenet_tx_reclaim() and bcmgenet_free_rx_buffers() are not using the
same struct device during unmap that was used for the map operation,
which makes DMA-API debugging warn about it. Fix this by always using
&priv->pdev->dev throughout the driver, using an identical device
reference for all map/unmap calls.

Fixes: 1c1008c7

 ("net: bcmgenet: add main driver file")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>