dt-bindings: mtd: qcom,nandc: Document the SDX75 NAND controller

Add new compatible for the QPIC NAND controller v2.1.1 used for SDX75 SoC.

SDX75 NAND controller has iommu support so define it in the properties
section.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Kaushal Kumar <quic_kaushalk@quicinc.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/qcom,nandc.yaml

@@ -11,7 +11,13 @@ maintainers:
 
 properties:
   compatible:
-    enum:
+    oneOf:
+      - items:
+          - enum:
+              - qcom,sdx75-nand
+          - const: qcom,sdx55-nand
+      - items:
+          - enum:
               - qcom,ipq806x-nand
               - qcom,ipq4019-nand
               - qcom,ipq6018-nand
@@ -95,6 +101,18 @@ allOf:
           items:
             - const: rxtx
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - qcom,sdx75-nand
+
+    then:
+      properties:
+        iommus:
+          maxItems: 1
+
   - if:
       properties:
         compatible: