arm: dts: imx6qdl-icore-rqs: Add eMMC node

Add usdhc4 node, which is eMMC for Engicam i.CoreM6 RQS modules.

eMMC Log:
--------
icorem6qdl-rqs> mmc dev 1
switch to partitions #0, OK
mmc1(part 0) is current device
icorem6qdl-rqs> mmcinfo
Device: FSL_SDHC
Manufacturer ID: fe
OEM: 14e
Name: MMC04
Tran Speed: 52000000
Rd Block Len: 512
MMC version 4.4.1
High Capacity: Yes
Capacity: 3.5 GiB
Bus Width: 4-bit
Erase Group Size: 512 KiB
HC WP Group Size: 4 MiB
User Capacity: 3.5 GiB
Boot Capacity: 16 MiB ENH
RPMB Capacity: 128 KiB ENH

Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>

arch/arm/dts/imx6qdl-icore-rqs.dtsi

@@ -107,6 +107,13 @@
 	status = "okay";
 };
 
+&usdhc4 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usdhc4>;
+	no-1-8-v;
+	status = "okay";
+};
+
 &iomuxc {
 	pinctrl_enet: enetgrp {
 		fsl,pins = <
@@ -167,4 +174,19 @@
 			MX6QDL_PAD_SD3_DAT3__SD3_DATA3 0x17070
 		>;
 	};
+
+	pinctrl_usdhc4: usdhc4grp {
+		fsl,pins = <
+			MX6QDL_PAD_SD4_CMD__SD4_CMD    0x17070
+			MX6QDL_PAD_SD4_CLK__SD4_CLK    0x10070
+			MX6QDL_PAD_SD4_DAT0__SD4_DATA0 0x17070
+			MX6QDL_PAD_SD4_DAT1__SD4_DATA1 0x17070
+			MX6QDL_PAD_SD4_DAT2__SD4_DATA2 0x17070
+			MX6QDL_PAD_SD4_DAT3__SD4_DATA3 0x17070
+			MX6QDL_PAD_SD4_DAT4__SD4_DATA4 0x17070
+			MX6QDL_PAD_SD4_DAT5__SD4_DATA5 0x17070
+			MX6QDL_PAD_SD4_DAT6__SD4_DATA6 0x17070
+			MX6QDL_PAD_SD4_DAT7__SD4_DATA7 0x17070
+		>;
+	};
 };