usb: early: ehci-dbgp: convert to readl_poll_timeout_atomic()

Use readl_poll_timeout_atomic() to simplify code

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1600668815-12135-2-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/early/ehci-dbgp.c

@@ -15,6 +15,7 @@
 #include <linux/console.h>
 #include <linux/errno.h>
 #include <linux/init.h>
+#include <linux/iopoll.h>
 #include <linux/pci_regs.h>
 #include <linux/pci_ids.h>
 #include <linux/usb/ch9.h>
@@ -161,17 +162,11 @@ static inline u32 dbgp_pid_read_update(u32 x, u32 tok)
 static int dbgp_wait_until_complete(void)
 {
 	u32 ctrl;
-	int loop = DBGP_TIMEOUT;
+	int ret;
 
-	do {
-		ctrl = readl(&ehci_debug->control);
-		/* Stop when the transaction is finished */
-		if (ctrl & DBGP_DONE)
-			break;
-		udelay(1);
-	} while (--loop > 0);
-
-	if (!loop)
+	ret = readl_poll_timeout_atomic(&ehci_debug->control, ctrl,
+				(ctrl & DBGP_DONE), 1, DBGP_TIMEOUT);
+	if (ret)
 		return -DBGP_TIMEOUT;
 
 	/*