amd-xgbe: Update DMA coherency values

Based on the IOMMU configuration, the current cache control settings can
result in possible coherency issues. The hardware team has recommended
new settings for the PCI device path to eliminate the issue.

Fixes: 6f595959

 ("amd-xgbe: Adjust register settings to improve performance")
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>