USB: enclose all depends on USB_OHCI_HCD within an if USB_OHCI_HCD block

This patch removes the various depends on USB_OHCI_HCD from the OHCI HCD
drivers and enclose them within an if USB_OHCI_HCD / endif block. The
Octeon OHCI HCD driver has been moved around to remain in this block.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>