net: phy: mdio-mux-bcm-iproc: use readl_poll_timeout() to simplify code

use readl_poll_timeout() to replace the poll codes for simplify
iproc_mdio_wait_for_idle() function
Signed-off-by: NDejin Zheng <zhengdejin5@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/mdio-mux-bcm-iproc.c

@@ -10,6 +10,7 @@
 #include <linux/phy.h>
 #include <linux/mdio-mux.h>
 #include <linux/delay.h>
+#include <linux/iopoll.h>
 
 #define MDIO_RATE_ADJ_EXT_OFFSET	0x000
 #define MDIO_RATE_ADJ_INT_OFFSET	0x004
@@ -78,18 +79,11 @@ static void mdio_mux_iproc_config(struct iproc_mdiomux_desc *md)
 
 static int iproc_mdio_wait_for_idle(void __iomem *base, bool result)
 {
-	unsigned int timeout = 1000; /* loop for 1s */
 	u32 val;
 
-	do {
-		val = readl(base + MDIO_STAT_OFFSET);
-		if ((val & MDIO_STAT_DONE) == result)
-			return 0;
-
-		usleep_range(1000, 2000);
-	} while (timeout--);
-
-	return -ETIMEDOUT;
+	return readl_poll_timeout(base + MDIO_STAT_OFFSET, val,
+				  (val & MDIO_STAT_DONE) == result,
+				  2000, 1000000);
 }
 
 /* start_miim_ops- Program and start MDIO transaction over mdio bus.