eth: make eth_address_set static

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/net/eth.c b/net/eth.c
index 76ffa05..eac4f7b 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -153,7 +153,7 @@
 		setenv("ethact", NULL);
 }
 
-int eth_address_set(unsigned char *addr)
+static int eth_address_set(unsigned char *addr)
 {
 	return memcmp(addr, "\0\0\0\0\0\0", 6);
 }