net/faraday: Match driver according to compatible property

This matches the driver with devices compatible with "faraday,ftgmac100"
declared in the device tree. Originally, device's name from device
tree for it.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>