mfd: 88pm805: msleep(1ms ~ 20ms) may not do what the caller intends

This code has been working since 2012, as limiting the time between
1ms and 3ms is unlikely to do any harm.

Soothes checkpatch warning:

  WARNING: msleep < 20ms can sleep for up to 20ms;
      see Documentation/timers/timers-howto.txt
  #161: FILE: drivers/mfd/88pm805.c:161:
  +	msleep(1);
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/88pm805.c

@@ -158,7 +158,7 @@ static int device_irq_init_805(struct pm80x_chip *chip)
 	 * PM805_INT_STATUS is under 32K clock domain, so need to
 	 * add proper delay before the next I2C register access.
 	 */
-	msleep(1);
+	usleep_range(1000, 3000);
 
 	if (ret < 0)
 		goto out;