microblaze: Add Emac driver to Makefile

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 6f0225b..5f6e195 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -61,6 +61,7 @@
 COBJS-y += tsi108_eth.o
 COBJS-y += uli526x.o
 COBJS-y += vsc7385.o
+COBJS-$(CONFIG_XILINX_EMAC) += xilinx_emac.o
 
 COBJS	:= $(COBJS-y)
 SRCS 	:= $(COBJS:.o=.c)