include: dwc3-omap-uboot: add a structure for populating dwc3-omap platform data

Added a structure to populate dwc3 omap platform data. The board file should
populate these platform data before invoking dwc3 omap driver.

This will be removed once dwc3-omap driver is adapted to use the driver model.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>