usbcore: remove unused argument in autosuspend

Thanks to several earlier patches, usb_autosuspend_device() and
usb_autoresume_device() are never called with a second argument other
than 1.  This patch (as819) removes the now-redundant argument.

It also consolidates some common code between those two routines,
putting it into a new subroutine called usb_autopm_do_device().  And
it includes a sizable kerneldoc update for the affected functions.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>