ARM: dts: omap4+: Add clocks to USB2 PHY node

The USB2 PHY driver expects named clocks for wakeup clock
and reference clock. Provide this information for USB2 PHY
nodes in OMAP4 and OMAP5 SoC DTS.

CC: Benoît Cousson <bcousson@baylibre.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>