Revert "USB: improve ehci_watchdog's side effect in CPU power management"

This reverts commit f0d781d5.

It was the wrong thing to do, and does not really do what it said
it did.

Cc: Yi Yang <yi.y.yang@intel.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>