Bluetooth: hci_bcm: Sleep instead of spinning

The driver calls mdelay(15) in the ->suspend, ->resume, ->runtime_suspend
and ->runtime_resume hook, however spinning for such a long period of
time is discouraged as per Documentation/timers/timers-howto.txt.

The use of mdelay() seems unnecessary, it is allowed to sleep in the
system sleep and runtime PM hooks (with the exception of ->suspend_noirq
and ->resume_noirq) and the driver itself also does not rely on a
non-sleeping ->runtime_resume as the only place where a synchronous
resume is performed, in bcm_dequeue(), is called from a work item in
hci_ldisc.c and hci_serdev.c.

So replace the mdelay(15) with msleep(15).

Note that the delay is inserted after asserting or deasserting the
device wake pin, but in bcm_gpio_set_power() that pin is asserted or
deasserted *without* observing a delay.  It is thus unclear if the delay
is necessary at all.  It is likewise unclear why it is exactly 15 ms,
the commit introducing it, 118612fb ("Bluetooth: hci_bcm: Add
suspend/resume PM functions"), does not provide a rationale.

Cc: Frédéric Danis <frederic.danis.oss@gmail.com>
Suggested-and-reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_bcm.c

@@ -656,7 +656,7 @@ static int bcm_suspend_device(struct device *dev)
 	}
 
 	bt_dev_dbg(bdev, "suspend, delaying 15 ms");
-	mdelay(15);
+	msleep(15);
 
 	return 0;
 }
@@ -675,7 +675,7 @@ static int bcm_resume_device(struct device *dev)
 	}
 
 	bt_dev_dbg(bdev, "resume, delaying 15 ms");
-	mdelay(15);
+	msleep(15);
 
 	/* When this executes, the device has woken up already */
 	if (bdev->is_suspended && bdev->hu) {