dt-bindings: mmc: Add information for DLL register properties

Add information regarding DLL register properties for getting board
specific configurations. These DLL register settings may vary from
board to board.
Signed-off-by: Sarthak Garg <sartgarg@codeaurora.org>
Link: https://lore.kernel.org/r/1590139950-7288-3-git-send-email-sartgarg@codeaurora.orgSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/sdhci-msm.txt

@@ -47,6 +47,13 @@ Required properties:
 	"cal"	- reference clock for RCLK delay calibration (optional)
 	"sleep"	- sleep clock for RCLK delay calibration (optional)
 
+- qcom,ddr-config: Certain chipsets and platforms require particular settings
+	for the DDR_CONFIG register. Use this field to specify the register
+	value as per the Hardware Programming Guide.
+
+- qcom,dll-config: Chipset and Platform specific value. Use this field to
+	specify the DLL_CONFIG register value as per Hardware Programming Guide.
+
 Example:
 
 	sdhc_1: sdhci@f9824900 {
@@ -64,6 +71,9 @@ Example:
 
 		clocks = <&gcc GCC_SDCC1_APPS_CLK>, <&gcc GCC_SDCC1_AHB_CLK>;
 		clock-names = "core", "iface";
+
+		qcom,dll-config = <0x000f642c>;
+		qcom,ddr-config = <0x80040868>;
 	};
 
 	sdhc_2: sdhci@f98a4900 {
@@ -81,4 +91,7 @@ Example:
 
 		clocks = <&gcc GCC_SDCC2_APPS_CLK>, <&gcc GCC_SDCC2_AHB_CLK>;
 		clock-names = "core", "iface";
+
+		qcom,dll-config = <0x0007642c>;
+		qcom,ddr-config = <0x80040868>;
 	};