net: add ICPlus PHY driver

The driver code was taken from Linux kernel source:
drivers/net/phy/icplus.c

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index af5f4b8..695873e 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -35,6 +35,7 @@
 COBJS-$(CONFIG_PHY_BROADCOM) += broadcom.o
 COBJS-$(CONFIG_PHY_DAVICOM) += davicom.o
 COBJS-$(CONFIG_PHY_ET1011C) += et1011c.o
+COBJS-$(CONFIG_PHY_ICPLUS) += icplus.o
 COBJS-$(CONFIG_PHY_LXT) += lxt.o
 COBJS-$(CONFIG_PHY_MARVELL) += marvell.o
 COBJS-$(CONFIG_PHY_MICREL) += micrel.o