arm64: dts: imx8mm-emcon: Remove iomuxc pinctrl-names

Remove a 'pinctrl-names' that is not associated with a corresponding
'pinctrl-names'.

This fixes the following schema warning:

imx8mm-emcon-avari.dtb: pinctrl@30330000: 'pinctrl-0' is a dependency of 'pinctrl-names'
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-emcon.dtsi

@@ -108,8 +108,6 @@ flash0: flash@0 {
 };
 
 &iomuxc {
-	pinctrl-names = "default";
-
 	pinctrl_csi_pwn: csi-pwn-grp {
 		fsl,pins = <
 			MX8MM_IOMUXC_GPIO1_IO07_GPIO1_IO7		0x19