dt-bindings: usb: Add "ulpi/serial/hsic" PHY types

Aside from the UTMI+ there are also ULPI, Serial and HSIC PHY types
that can be specified in the phy_type HCD property. Add them to the
enumeration of the acceptable values.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-5-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>