net: stmmac: XGMAC support for mdio C22 addr > 3

For XGMAC versions < 2.2 number of supported mdio C22 addresses is
restricted to 3. From XGMAC version 2.2 there are no restrictions on
the C22 addresses, it supports all valid mdio addresses(0 to 31).

Signed-off-by: Rohan G Thomas <rohan.g.thomas@intel.com>
Acked-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>