dt-bindings: usb: cdns,usb3: Add cdns,phyrst-a-enable property

Controller version 0x0002450D has USB2 PHY RX sensitivity issues
that needs to be worked around by enabling phyrst-a-enable bit
in PHYRST_CFG register.

There is no way to know controller version before device controller
is started and the workaround needs to be applied for both host and
device modes, so we add this DT property.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Felipe Balbi <balbi@kernel.org>