serdev: Replace poll loop by readx_poll_timeout() macro

The readx_poll_timeout() consolidates the necessary code under
macro. Replace current code with it.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221114151813.37294-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/serdev.h

@@ -7,6 +7,7 @@
 
 #include <linux/types.h>
 #include <linux/device.h>
+#include <linux/iopoll.h>
 #include <linux/uaccess.h>
 #include <linux/termios.h>
 #include <linux/delay.h>
@@ -279,18 +280,10 @@ static inline bool serdev_device_get_cts(struct serdev_device *serdev)
 
 static inline int serdev_device_wait_for_cts(struct serdev_device *serdev, bool state, int timeout_ms)
 {
-	unsigned long timeout;
 	bool signal;
 
-	timeout = jiffies + msecs_to_jiffies(timeout_ms);
-	while (time_is_after_jiffies(timeout)) {
-		signal = serdev_device_get_cts(serdev);
-		if (signal == state)
-			return 0;
-		usleep_range(1000, 2000);
-	}
-
-	return -ETIMEDOUT;
+	return readx_poll_timeout(serdev_device_get_cts, serdev, signal, signal == state,
+				  2000, timeout_ms * 1000);
 }
 
 static inline int serdev_device_set_rts(struct serdev_device *serdev, bool enable)