davinci: USB clocks for Omapl138-Hawkboard

This patch adds USB1.1 and USB2.0 clocks for the Hawkboard-L138 system

Signed-off-by: Victor Rodriguez <vm.rod25@gmail.com>
Tested-by: Rene Gonzalez <renegs.2378@gmail.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>