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/include/linux/acpi.h b/include/linux/acpi.h
index 913b49f..90e4ed1 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -163,6 +163,11 @@
 	return (int)cpuid < 0;
 }
 
+static inline bool invalid_phys_cpuid(phys_cpuid_t phys_id)
+{
+	return phys_id == PHYS_CPUID_INVALID;
+}
+
 #ifdef CONFIG_ACPI_HOTPLUG_CPU
 /* Arch dependent functions for cpu hotplug support */
 int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, int *pcpu);