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/tcm-bf518/tcm-bf518.c b/board/tcm-bf518/tcm-bf518.c
index 5964059..5d25fcd 100644
--- a/board/tcm-bf518/tcm-bf518.c
+++ b/board/tcm-bf518/tcm-bf518.c
@@ -11,7 +11,6 @@
 #include <net.h>
 #include <netdev.h>
 #include <asm/blackfin.h>
-#include <asm/net.h>
 #include <asm/mach-common/bits/otp.h>
 #include <asm/sdh.h>
 
@@ -47,7 +46,7 @@
 
 	if (!valid_mac) {
 		puts("Warning: Generating 'random' MAC address\n");
-		bfin_gen_rand_mac(mac_addr);
+		eth_random_addr(mac_addr);
 	}
 
 	eth_setenv_enetaddr("ethaddr", mac_addr);