blackfin: replace bfin_gen_rand_mac() with eth_random_addr()

bfin_gen_rand_mac() uses __DATE__ as the seed for random ethernet
address. This makes the build non-deterministic.

In the first place, it should not be implemented as a Bfin-specific
function. Use eth_random_addr() instead.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sonic Zhang <sonic.zhang@analog.com>
diff --git a/board/bct-brettl2/bct-brettl2.c b/board/bct-brettl2/bct-brettl2.c
index de5b9ff..6be9b18 100644
--- a/board/bct-brettl2/bct-brettl2.c
+++ b/board/bct-brettl2/bct-brettl2.c
@@ -12,7 +12,6 @@
 #include <asm/blackfin.h>
 #include <asm/portmux.h>
 #include <asm/gpio.h>
-#include <asm/net.h>
 #include <net.h>
 #include <netdev.h>
 #include <miiphy.h>
@@ -33,7 +32,7 @@
 static void board_init_enetaddr(uchar *mac_addr)
 {
 	puts("Warning: Generating 'random' MAC address\n");
-	bfin_gen_rand_mac(mac_addr);
+	eth_random_addr(mac_addr);
 	eth_setenv_enetaddr("ethaddr", mac_addr);
 }