phy: Add lan966x ethernet serdes PHY driver

Add the Microchip lan966x ethernet serdes PHY driver for interfaces
available in the lan966x SoC.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20211116100818.1615762-4-horatiu.vultur@microchip.com


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