ARM: dts: Configure USB host for 37xx-evm

Looks like nobody bothered to configure USB host for 37xx-evm
when we converted things to device tree, so let's add it. This
is similar to beagleboard configuration with few extra quirks
to configure the port. And as with beagleboard, OHCI won't work
because there is no USB LS/FS PHY. A HS USB hub is needed to use
devices like keyboard and mice.

Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>