pvmfw: Pre-populate pviommu nodes

This CL also add dtc parameter -@ to compile dtb file with pviommu
symbols. They would be used by assign device nodes.

However, -@ option also generates /__symbols__ for all symbols including
swiotlb, intc, and clk. But the list is limited so performance / size
impact would be insignificant.

Bug: 277993056
Test: fdtdump Check generated DTBO contains pviommu for followings: \
      - 10 pre-populated pviommu nodes with their own phandles.     \
      - /__symbols__ contains following properties:                 \
        - swiotlb = "/reserved-memory/restricted_dma_reserved";     \
        - intc = "/intc";                                           \
        - clk = "/pclk@3M";                                         \
        - pviommu_0 = "/pviommu0";                                  \
          ...                                                       \
Change-Id: I9d684029aebe13ddb3a526c7f13a5ff795850461
diff --git a/pvmfw/platform.dts b/pvmfw/platform.dts
index cb8e30d..4a269c3 100644
--- a/pvmfw/platform.dts
+++ b/pvmfw/platform.dts
@@ -261,4 +261,64 @@
 		clock-frequency = <10>;
 		timeout-sec = <8>;
 	};
+
+	pviommu_0: pviommu0 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_1: pviommu1 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_2: pviommu2 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_3: pviommu3 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_4: pviommu4 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_5: pviommu5 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_6: pviommu6 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_7: pviommu7 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_8: pviommu8 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
+
+	pviommu_9: pviommu9 {
+		compatible = "pkvm,pviommu";
+		id = <PLACEHOLDER>;
+		#iommu-cells = <0>;
+	};
 };