ARM: dts: OMAP5: Add dr_mode for dwc3

Added dr_mode property in dwc3 and set its default mode to device.

Signed-off-by: George Cherian <george.cherian@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>