efi_loader: Add network access support

We can now successfully boot EFI applications from disk, but users
may want to also run them from a PXE setup.

This patch implements rudimentary network support, allowing a payload
to send and receive network packets.

With this patch, I was able to successfully run grub2 with network
access inside of QEMU's -M xlnx-ep108.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/net/net.c b/net/net.c
index fba111e..1e1d23d 100644
--- a/net/net.c
+++ b/net/net.c
@@ -146,7 +146,7 @@
 /* Ethernet bcast address */
 const u8 net_bcast_ethaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 const u8 net_null_ethaddr[6];
-#ifdef CONFIG_API
+#if defined(CONFIG_API) || defined(CONFIG_EFI_LOADER)
 void (*push_packet)(void *, int len) = 0;
 #endif
 /* Network loop state */
@@ -1054,7 +1054,7 @@
 	if (len < ETHER_HDR_SIZE)
 		return;
 
-#ifdef CONFIG_API
+#if defined(CONFIG_API) || defined(CONFIG_EFI_LOADER)
 	if (push_packet) {
 		(*push_packet)(in_packet, len);
 		return;