sandbox: eth: Add network support to sandbox

Add basic network support to sandbox which includes a network driver.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 5a5269a..b9f5db3 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -51,6 +51,7 @@
 obj-$(CONFIG_PCNET) += pcnet.o
 obj-$(CONFIG_RTL8139) += rtl8139.o
 obj-$(CONFIG_RTL8169) += rtl8169.o
+obj-$(CONFIG_ETH_SANDBOX) += sandbox.o
 obj-$(CONFIG_SH_ETHER) += sh_eth.o
 obj-$(CONFIG_SMC91111) += smc91111.o
 obj-$(CONFIG_SMC911X) += smc911x.o