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

Use readl_poll_timeout_atomic() to simplify code

Cc: "Eric W. Biederman" <[e-mail]>
Cc: Petr Mladek <[e-mail]>
Signed-off-by: Chunfeng Yun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/early/ehci-dbgp.c

···
 #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>
···
 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;
 
 	/*