ACPI / processor: Introduce ARCH_MIGHT_HAVE_ACPI_PDC

The use of _PDC is deprecated in ACPI 3.0 in favor of _OSC,
as ARM platform is supported only in ACPI 5.0 or higher version,
_PDC will not be used in ARM platform, so make Make _PDC only for
platforms with Intel CPUs.

Introduce ARCH_MIGHT_HAVE_ACPI_PDC and move _PDC related code in
ACPI processor driver into a single file processor_pdc.c, make x86
and ia64 select it when ACPI is enabled.

This patch also use pr_* to replace printk to fix the checkpatch
warning and factor acpi_processor_alloc_pdc() a little bit to
avoid duplicate pr_err() code.

Suggested-by: Robert Richter <rric@kernel.org>
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/Kconfig b/drivers/acpi/Kconfig
index 970524c..3f5f745 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -45,6 +45,9 @@
 config ACPI_LEGACY_TABLES_LOOKUP
 	bool
 
+config ARCH_MIGHT_HAVE_ACPI_PDC
+	bool
+
 config ACPI_SLEEP
 	bool
 	depends on SUSPEND || HIBERNATION