USB: remove references to dev.power.power_state

This revised patch (as891b) removes two unnecessary references to
intf->dev.power.power_state from usb-storage, and replaces a reference
to root_hub->dev.power.power_state with a check of hcd->state.  This
is in preparation for the removal of dev.power.power_state, which is
already deprecated.

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