ACPICA: IORT: Add PMCG node supprt

PMCG nodes were added by IORT revision C, with the unfortunate oversight
that it only defined a single base address, and thus was incapable of
properly describing PMCG implementations with PMCG_CFGR.RELOC_CTRS = 1,
where the counters are in a separate page from the control registers.

Revision D corrects this by clarifying the existing field as the page 0
base address and adding a second field to describe the page 1 address
when implemented. With the spec now fit for purpose, let's support it.

Signed-off-by: Robin Murphy <[e-mail]>
Signed-off-by: Erik Schmauss <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

include/acpi/actbl2.h

···
 	ACPI_IORT_NODE_NAMED_COMPONENT = 0x01,
 	ACPI_IORT_NODE_PCI_ROOT_COMPLEX = 0x02,
 	ACPI_IORT_NODE_SMMU = 0x03,
-	ACPI_IORT_NODE_SMMU_V3 = 0x04
+	ACPI_IORT_NODE_SMMU_V3 = 0x04,
+	ACPI_IORT_NODE_PMCG = 0x05
 };
 
 struct acpi_iort_id_mapping {
···
 #define ACPI_IORT_SMMU_V3_COHACC_OVERRIDE   (1)
 #define ACPI_IORT_SMMU_V3_HTTU_OVERRIDE     (3<<1)
 #define ACPI_IORT_SMMU_V3_PXM_VALID         (1<<3)
+
+struct acpi_iort_pmcg {
+	u64 page0_base_address;
+	u32 overflow_gsiv;
+	u32 node_reference;
+	u64 page1_base_address;
+};
 
 /*******************************************************************************
  *