phy: intel: Add Keem Bay USB PHY support

Add PHY driver for the USB3.1 and USB 2.0 PHYs found on Intel
Keem Bay SoC. This driver takes care of enabling the required
USB susbsystem (USS) clocks, initializing the PHYs and turning
on/off the USB dwc3 core.

Signed-off-by: Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201116120831.32641-3-wan.ahmad.zainie.wan.mohamad@intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>