USB: ohci-at91: fix PIO handling in relation with number of ports

If the number of ports present on the SoC/board is not the maximum
and that the platform data is not filled with all data, there is
an easy way to mess the PIO setup for this interface.
This quick fix addresses mis-configuration in USB host platform data
that is common in at91 boards since commit 0ee6d1ee

 (USB: ohci-at91:
change maximum number of ports) that did not modified the associatd
board files.

Reported-by: Klaus Falkner <klaus.falkner@solectrix.de>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Stable <stable@vger.kernel.org> [3.4+]
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>