dt-bindings: Add Marvell PXA1928 USB and HSIC PHY bindings

Add PHY binding for Marvell PXA1928 SOC's USB and HSIC PHYs.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>