ACPI: PRM: Find PRMT table before parsing it

Find and verify PRMT before parsing it, which eliminates a
warning on machines without PRMT:

	[    7.197173] ACPI: PRMT not present

Fixes: cefc7ca ("ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype")
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: 5.14+ <stable@vger.kernel.org> # 5.14+
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/prmt.c

@@ -288,10 +288,18 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
 
 void __init init_prmt(void)
 {
+	struct acpi_table_header *tbl;
 	acpi_status status;
-	int mc = acpi_table_parse_entries(ACPI_SIG_PRMT, sizeof(struct acpi_table_prmt) +
+	int mc;
+
+	status = acpi_get_table(ACPI_SIG_PRMT, 0, &tbl);
+	if (ACPI_FAILURE(status))
+		return;
+
+	mc = acpi_table_parse_entries(ACPI_SIG_PRMT, sizeof(struct acpi_table_prmt) +
 					  sizeof (struct acpi_table_prmt_header),
 					  0, acpi_parse_prmt, 0);
+	acpi_put_table(tbl);
 	/*
 	 * Return immediately if PRMT table is not present or no PRM module found.
 	 */