nds32: ftmac100: Fix write mac addr fail problem.

After soft reset complete, write mac address immediately will fail.
Add delay to work around this problem.

Signed-off-by: rick <rick@andestech.com>
diff --git a/drivers/net/ftmac100.c b/drivers/net/ftmac100.c
index 4e45f00..e64bf3d 100644
--- a/drivers/net/ftmac100.c
+++ b/drivers/net/ftmac100.c
@@ -40,7 +40,12 @@
 	writel (FTMAC100_MACCR_SW_RST, &ftmac100->maccr);
 
 	while (readl (&ftmac100->maccr) & FTMAC100_MACCR_SW_RST)
-		;
+		mdelay(1);
+	/*
+	 * When soft reset complete, write mac address immediately maybe fail somehow
+	 *  Wait for a while can avoid this problem
+	 */
+	mdelay(1);
 }
 
 /*