phy: Add Marvell USB 2.0 OTG 28nm PHY

Add driver for USB 28nm PHY found in Marvell PXA1928 SOC.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>