USB: ohci-jz4740: Fix uninitialized variable warning

The ret variable is not initialized in all code paths of the
ohci_jz4740_hub_control function. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>