net: rswitch: Add Renesas Ethernet Switch

This patch adds Ethernet Switch support that found on R-Car S4
(r8a779f0) SoC. This is extracted from multiple patches from
downstream BSP, with additional rework of the network device
registration.

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
[Marek: Rework the driver to support all ports via subdrivers.
        Split the driver up, add generic PHY framework support.
	Generic code clean ups.]
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 5c29e63..09039a2 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -752,6 +752,14 @@
 	  This driver provides Rockchip SoCs network support based on the
 	  Synopsys Designware driver.
 
+config RENESAS_ETHER_SWITCH
+	bool "Renesas Ethernet Switch support"
+	depends on DM_ETH && R8A779F0
+	select PHYLIB
+	help
+	  This driver implements support for the Renesas Ethernet Switch
+	  which is available on R-Car S4 SoC (r8a779f0).
+
 config RENESAS_RAVB
 	bool "Renesas Ethernet AVB MAC"
 	depends on RCAR_64