amd-xgbe: Limit the I2C error messages that are output

When I2C communication fails, it tends to always fail. Rather than
continuously issue an error message (once per second in most cases),
change the message to be issued just once.

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