USB: Add USB 2.0 to ssb ohci driver

This adds USB 2.0 support to ssb ohci driver.
This patch was used in OpenWRT for a long time now.

CC: Steve Brown <sbrown@cortland.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>