nds32: Use getenv_ulong() in place of getenv(), strtoul

This changes the board code to use the new getenv_ulong() function.

Signed-off-by: Macpaul Lin <macpaul@andestech.com>
diff --git a/arch/nds32/lib/board.c b/arch/nds32/lib/board.c
index 1776a72..2fd0e93 100644
--- a/arch/nds32/lib/board.c
+++ b/arch/nds32/lib/board.c
@@ -50,13 +50,7 @@
 #endif
 static int init_baudrate(void)
 {
-	char tmp[64];	/* long enough for environment variables */
-	int i = getenv_f("baudrate", tmp, sizeof(tmp));
-
-	gd->bd->bi_baudrate = gd->baudrate = (i > 0)
-			? (int) simple_strtoul(tmp, NULL, 10)
-			: CONFIG_BAUDRATE;
-
+	gd->baudrate = getenv_ulong("baudrate", 10, CONFIG_BAUDRATE);
 	return 0;
 }
 
@@ -400,9 +394,7 @@
 #endif
 
 	/* Initialize from environment */
-	s = getenv("loadaddr");
-	if (s != NULL)
-		load_addr = simple_strtoul(s, NULL, 16);
+	load_addr = getenv_ulong("loadaddr", 16, load_addr);
 
 #if defined(CONFIG_CMD_NET)
 	s = getenv("bootfile");