sunxi: fix CONFIG_SUNXI_EMAC references

fixes CONFIG_SUNXI_EMAC references from drivers/net/Makefile and
include/configs/sunxi-common.h likely forgotten in:
	commit abc3e4df59f5 ("sunxi: Convert SUNXI_EMAC to Kconfig")

Signed-off-by: Artturi Alm <artturi.alm@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 94a4fd8..ac5443c 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -21,7 +21,7 @@
 obj-$(CONFIG_E1000) += e1000.o
 obj-$(CONFIG_E1000_SPI) += e1000_spi.o
 obj-$(CONFIG_EEPRO100) += eepro100.o
-obj-$(CONFIG_SUNXI_EMAC) += sunxi_emac.o
+obj-$(CONFIG_SUN4I_EMAC) += sunxi_emac.o
 obj-$(CONFIG_SUN8I_EMAC) += sun8i_emac.o
 obj-$(CONFIG_ENC28J60) += enc28j60.o
 obj-$(CONFIG_EP93XX) += ep93xx_eth.o