arm64: dts: imx8mq-sr-som: Align pin configuration group names with schema

Device tree schema expects pin configuration groups to end with 'grp'
suffix, otherwise dtbs_check complain with a warning like:

    ... do not match any of the regexes: 'grp$', 'pinctrl-[0-9]+'
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-sr-som.dtsi

@@ -275,7 +275,7 @@ MX8MQ_IOMUXC_SD1_RESET_B_USDHC1_RESET_B		0xc1
 		>;
 	};
 
-	pinctrl_usdhc1_100mhz: usdhc1grp100mhz {
+	pinctrl_usdhc1_100mhz: usdhc1-100mhzgrp {
 		fsl,pins = <
 			MX8MQ_IOMUXC_SD1_CLK_USDHC1_CLK			0x8d
 			MX8MQ_IOMUXC_SD1_CMD_USDHC1_CMD			0xcd
@@ -292,7 +292,7 @@ MX8MQ_IOMUXC_SD1_RESET_B_USDHC1_RESET_B		0xc1
 		>;
 	};
 
-	pinctrl_usdhc1_200mhz: usdhc1grp200mhz {
+	pinctrl_usdhc1_200mhz: usdhc1-200mhzgrp {
 		fsl,pins = <
 			MX8MQ_IOMUXC_SD1_CLK_USDHC1_CLK			0x9f
 			MX8MQ_IOMUXC_SD1_CMD_USDHC1_CMD			0xdf