ARM: dts: omap5-uevm: Provide USB Host PHY clock frequency

USB Host PHY clock on port 2 must be configured to 19.2MHz.
Provide this information.

Cc: Sricharan R <r.sricharan@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>