phy: renesas: Add PCS driver for Renesas R-Car X5H R8A78000

phy: renesas: Add PCS driver for Renesas R-Car X5H R8A78000

Add support for the Ethernet Physical Coding Sublayer (PCS) controller
on R-Car Gen5 SoCs, specifically the Renesas R-Car X5H R8A78000.

The controller is based on the SERDES infrastructure used in previous
R-Car generations, with updates for Gen5 register layout and features.

Because majority of this driver is SoC-specific register programming,
the majority of this driver is different enough from R8A779F0 SerDes
driver to justify its own driver. Deduplication of the remaining bits
of code does not yield any improvement.

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com>
Signed-off-by: Tam Nguyen <tam.nguyen.xa@renesas.com>
Signed-off-by: Thanh Quan <thanh.quan.xn@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
[Marek: Add missing clk_bulk_disable() in fail path.
        Drop always-true aneg_on setting.
	Reduce poll delay from 100s to 100ms.
	Use bulk reset operations to finalize reset handling.]