arm64: dts: imx8mn-var-som-symphony: adapt FEC pinctrl for SOMs with onboard PHY

The VAR SOM symphony carrier board can be used with SOMs which have a
soldered ethernet PHY onboard and with SOMs which don't have one.

For SOMs with an onboard PHY, the PHY on the cartrier board is not
used, and GPIO1_IO9 is used as a reset line to the onboard PHY.

For SOMs without an onboard PHY, the PHY on the carrier board is
used. For this configuration, pca9534 GPIO 5 (located on the carrier
board) is used as a reset line to the PHY, and GPIO1_IO9 is not
used.

GPIO1_IO9 is not connected to any user-accessible pins or functions,
and leaving it enabled in the mux pinctrl for both configurations is
safe.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mn-var-som-symphony.dts

@@ -152,46 +152,6 @@ &usbotg1 {
 	extcon = <&extcon_usbotg1>, <&extcon_usbotg1>;
 };
 
-&pinctrl_fec1 {
-	fsl,pins = <
-		MX8MN_IOMUXC_ENET_MDC_ENET1_MDC			0x3
-		MX8MN_IOMUXC_ENET_MDIO_ENET1_MDIO		0x3
-		MX8MN_IOMUXC_ENET_TD3_ENET1_RGMII_TD3		0x1f
-		MX8MN_IOMUXC_ENET_TD2_ENET1_RGMII_TD2		0x1f
-		MX8MN_IOMUXC_ENET_TD1_ENET1_RGMII_TD1		0x1f
-		MX8MN_IOMUXC_ENET_TD0_ENET1_RGMII_TD0		0x1f
-		MX8MN_IOMUXC_ENET_RD3_ENET1_RGMII_RD3		0x91
-		MX8MN_IOMUXC_ENET_RD2_ENET1_RGMII_RD2		0x91
-		MX8MN_IOMUXC_ENET_RD1_ENET1_RGMII_RD1		0x91
-		MX8MN_IOMUXC_ENET_RD0_ENET1_RGMII_RD0		0x91
-		MX8MN_IOMUXC_ENET_TXC_ENET1_RGMII_TXC		0x1f
-		MX8MN_IOMUXC_ENET_RXC_ENET1_RGMII_RXC		0x91
-		MX8MN_IOMUXC_ENET_RX_CTL_ENET1_RGMII_RX_CTL	0x91
-		MX8MN_IOMUXC_ENET_TX_CTL_ENET1_RGMII_TX_CTL	0x1f
-		/* Remove the MX8MM_IOMUXC_GPIO1_IO09_GPIO1_IO9 as not used */
-	>;
-};
-
-&pinctrl_fec1_sleep {
-	fsl,pins = <
-		MX8MN_IOMUXC_ENET_MDC_GPIO1_IO16		0x120
-		MX8MN_IOMUXC_ENET_MDIO_GPIO1_IO17		0x120
-		MX8MN_IOMUXC_ENET_TD3_GPIO1_IO18		0x120
-		MX8MN_IOMUXC_ENET_TD2_GPIO1_IO19		0x120
-		MX8MN_IOMUXC_ENET_TD1_GPIO1_IO20		0x120
-		MX8MN_IOMUXC_ENET_TD0_GPIO1_IO21		0x120
-		MX8MN_IOMUXC_ENET_RD3_GPIO1_IO29		0x120
-		MX8MN_IOMUXC_ENET_RD2_GPIO1_IO28		0x120
-		MX8MN_IOMUXC_ENET_RD1_GPIO1_IO27		0x120
-		MX8MN_IOMUXC_ENET_RD0_GPIO1_IO26		0x120
-		MX8MN_IOMUXC_ENET_TXC_GPIO1_IO23		0x120
-		MX8MN_IOMUXC_ENET_RXC_GPIO1_IO25		0x120
-		MX8MN_IOMUXC_ENET_RX_CTL_GPIO1_IO24		0x120
-		MX8MN_IOMUXC_ENET_TX_CTL_GPIO1_IO22		0x120
-		/* Remove the MX8MM_IOMUXC_GPIO1_IO09_GPIO1_IO9 as not used */
-	>;
-};
-
 &iomuxc {
 	pinctrl_captouch: captouchgrp {
 		fsl,pins = <