net: axienet: Clean up device used for DMA calls

[ Upstream commit 17882fd4 ]

Instead of using lp->ndev.parent to find the correct device to use for
DMA API calls, just use the dev attribute in the device structure.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5a6caa2c ("net: xilinx: axienet: Fix packet counting")
Signed-off-by: Sasha Levin <sashal@kernel.org>