dt-bindings: phy: uniphier-ahci: Add bindings for Pro4 SoC

Update AHCI-PHY binding document for UniPhier Pro4 SoC. Add a compatible
string, clock and reset lines for the SoC to the document.

Pro4 AHCI-PHY needs to control additional GIO clock line and reset lines
("pm", "tx", and "rx").

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1635503947-18250-8-git-send-email-hayashi.kunihiko@socionext.com


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