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/cm-bf537e/cm-bf537e.c b/board/cm-bf537e/cm-bf537e.c
index 8daf3ad..e79f90f 100644
--- a/board/cm-bf537e/cm-bf537e.c
+++ b/board/cm-bf537e/cm-bf537e.c
@@ -12,7 +12,6 @@
 #include <net.h>
 #include <netdev.h>
 #include <asm/blackfin.h>
-#include <asm/net.h>
 #include "gpio_cfi_flash.h"
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -32,7 +31,7 @@
 		return;
 
 	printf("Warning: %s: generating 'random' MAC address\n", var);
-	bfin_gen_rand_mac(enetaddr);
+	eth_random_addr(enetaddr);
 	eth_setenv_enetaddr(var, enetaddr);
 }