net: Use int instead of u8 for boolean flag

On some archs masking the parameter is inefficient, so don't use u8.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reported-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/net/eth.c b/net/eth.c
index 9ad15cd..b86994e 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -321,7 +321,7 @@
  * mcast_addr: multicast ipaddr from which multicast Mac is made
  * join: 1=join, 0=leave.
  */
-int eth_mcast_join(IPaddr_t mcast_ip, u8 join)
+int eth_mcast_join(IPaddr_t mcast_ip, int join)
 {
 	u8 mcast_mac[6];
 	if (!eth_current || !eth_current->mcast)