phy: renesas: Add Renesas Ethernet SERDES driver for R-Car S4-8

Add Renesas Ethernet SERDES driver for R-Car S4-8 (r8a779f0).
The datasheet describes initialization procedure without any information
about registers' name/bits. So, this is all black magic to initialize
the hardware. Especially, all channels should be initialized at once.

This driver is imported and adjusted from Linux 6.3-rc1 commit:
50133cd3e8dd1 ("phy: renesas: r8a779f0-eth-serdes: Remove retry code in .init()")

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index cf4d590..7a2d54f 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig
@@ -285,5 +285,6 @@
 source "drivers/phy/cadence/Kconfig"
 source "drivers/phy/ti/Kconfig"
 source "drivers/phy/qcom/Kconfig"
+source "drivers/phy/renesas/Kconfig"
 
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