PCI / PM: Update runtime PM documentation for PCI devices

Section 3.2 "Device Runtime Power Management" of pci.txt has become
outdated, so update it to correctly reflect the current code flow.

Also update the comment in local_pci_probe() to document the fact
that pm_runtime_put_noidle() is not the only runtime PM helper
function that can be used to decrement the device's runtime PM
usage counter in .probe().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index dd652f2..108a311 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -299,9 +299,10 @@
 	 * Unbound PCI devices are always put in D0, regardless of
 	 * runtime PM status.  During probe, the device is set to
 	 * active and the usage count is incremented.  If the driver
-	 * supports runtime PM, it should call pm_runtime_put_noidle()
-	 * in its probe routine and pm_runtime_get_noresume() in its
-	 * remove routine.
+	 * supports runtime PM, it should call pm_runtime_put_noidle(),
+	 * or any other runtime PM helper function decrementing the usage
+	 * count, in its probe routine and pm_runtime_get_noresume() in
+	 * its remove routine.
 	 */
 	pm_runtime_get_sync(dev);
 	pci_dev->driver = pci_drv;