arm: omap: usb: clock entries for omap3 and omap4

The devices of clocks are set to usbhs, so that
only usbhs common driver can invoke these clocks.
The dummy per port clocks are added to omap3
clock data base. This helps to invoke common
clock get APIs for omap3 and omap4.

Signed-off-by: Keshava Munegowda <keshava_mgowda@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>