ACPI / processor: Introduce invalid_phys_cpuid()

Introduce invalid_phys_cpuid() to identify cpu with invalid
physical ID, then used it as replacement of the direct comparisons
with PHYS_CPUID_INVALID.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 62c846b..92a5f73 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -170,7 +170,7 @@
 	acpi_status status;
 	int ret;
 
-	if (pr->phys_id == PHYS_CPUID_INVALID)
+	if (invalid_phys_cpuid(pr->phys_id))
 		return -ENODEV;
 
 	status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
@@ -264,7 +264,7 @@
 
 	pr->phys_id = acpi_get_phys_id(pr->handle, device_declaration,
 					pr->acpi_id);
-	if (pr->phys_id == PHYS_CPUID_INVALID)
+	if (invalid_phys_cpuid(pr->phys_id))
 		acpi_handle_debug(pr->handle, "failed to get CPU physical ID.\n");
 
 	pr->id = acpi_map_cpuid(pr->phys_id, pr->acpi_id);