amd-xgbe: Update the BelFuse quirk to support SGMII

Instead of using a quirk to make the BelFuse 1GBT-SFP06 part look like
a 1000baseX part, program the SFP PHY to support SGMII and 10/100/1000
baseT.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>