dt-bindings: ufs: exynos-ufs: add io-coherency property

Add "samsung,sysreg" regmap and the offset to the ufs shareability
register for setting io coherency of the samsung ufs. "dma-coherent"
property is also required because the driver code needs to know.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211018124216.153072-13-chanho61.park@samsung.com

Documentation/devicetree/bindings/ufs/samsung,exynos-ufs.yaml

@@ -54,6 +54,14 @@ properties:
   phy-names:
     const: ufs-phy
 
+  samsung,sysreg:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    description: Should be phandle/offset pair. The phandle to the syscon node
+                 which indicates the FSYSx sysreg interface and the offset of
+                 the control register for UFS io coherency setting.
+
+  dma-coherent: true
+
 required:
   - compatible
   - reg