dt-bindings: phy: Add Intel Keem Bay USB PHY bindings

Binding description for Intel Keem Bay USB PHY.

Signed-off-by: Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201116120831.32641-2-wan.ahmad.zainie.wan.mohamad@intel.com


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