net: add a define for the number of packets received as batch

With a define for the magic number of packets received as batch
we can make sure that the EFI network stack caches the same amount
of packets.

Signed-off-by: Patrick Wildt <patrick@blueri.se>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/net/eth-uclass.c b/net/eth-uclass.c
index 4424d59..e14695c 100644
--- a/net/eth-uclass.c
+++ b/net/eth-uclass.c
@@ -383,7 +383,7 @@
 
 	/* Process up to 32 packets at one time */
 	flags = ETH_RECV_CHECK_DEVICE;
-	for (i = 0; i < 32; i++) {
+	for (i = 0; i < ETH_PACKETS_BATCH_RECV; i++) {
 		ret = eth_get_ops(current)->recv(current, flags, &packet);
 		flags = 0;
 		if (ret > 0)