ARM: cns3xxx: use OHCI platform driver

This patch converts the cns3xxx platform to use the ohci-platform driver which
is now suitable for use.

A previous patch converted the cns3xxx platform to use the ehci-platform
driver, and thus introduced the need to have power_{on,off} callbacks.
Since both the EHCI and OHCI platform drivers use the same same power_{on,off}
callbacks now, rename them to cns3xx_usb_power_{on,off} to show that they are
shared.

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