USB / PM: Drop CONFIG_PM_RUNTIME from the USB core

After commit b2b49ccbdd54 (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so quite a few
depend on CONFIG_PM (or even dropped in some cases).

Replace CONFIG_PM_RUNTIME with CONFIG_PM in the USB core code
and documentation.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index ca7b964..851006a 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -305,7 +305,7 @@
 		}
 	}
 
-#ifdef	CONFIG_PM_RUNTIME
+#ifdef	CONFIG_PM
 	if (ehci->no_selective_suspend && device_can_wakeup(&pdev->dev))
 		ehci_warn(ehci, "selective suspend/wakeup unavailable\n");
 #endif