phy: socionext: Add UniPhier AHCI PHY driver support

Add a driver for PHY interface built into ahci controller implemented
in UniPhier SoCs. This supports PXs2 and PXs3 SoCs.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1598352071-26675-3-git-send-email-hayashi.kunihiko@socionext.com


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