dt-bindings: phy: intel: Add Keem Bay eMMC PHY bindings

Binding description for Intel Keem Bay eMMC 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/20200913235522.4316-3-wan.ahmad.zainie.wan.mohamad@intel.com


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