net: phy: icplus: use PHY_ID_MATCH_EXACT() for IP101A/G

According to the datasheet of the IP101A/G there is no revision field
and MII_PHYSID2 always reads as 0x0c54. Use PHY_ID_MATCH_EXACT() then.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>