[CPUFREQ] Enable ACPI PDC handshake for VIA/Centaur CPUs

In commit 0de51088e6a82bc8413d3ca9e28bbca2788b5b53, we introduced the
use of acpi-cpufreq on VIA/Centaur CPU's by removing a vendor check for
VENDOR_INTEL.  However, as it turns out, at least the Nano CPU's also
need the PDC (processor driver capabilities) handshake in order to
activate the methods required for acpi-cpufreq.

Since arch_acpi_processor_init_pdc() contains another vendor check for
Intel, the PDC is not initialized on VIA CPU's.  The resulting behavior
of a current mainline kernel on such systems is:  acpi-cpufreq
loads and it indicates CPU frequency changes.  However, the CPU stays at
a single frequency

This trivial patch ensures that init_intel_pdc() is called on Intel and
VIA/Centaur CPU's alike.

Signed-off-by: Harald Welte <HaraldWelte@viatech.com>
Signed-off-by: Dave Jones <davej@redhat.com>

arch/x86/kernel/acpi/processor.c

@@ -79,7 +79,8 @@ void arch_acpi_processor_init_pdc(struct acpi_processor *pr)
 	struct cpuinfo_x86 *c = &cpu_data(pr->id);
 
 	pr->pdc = NULL;
-	if (c->x86_vendor == X86_VENDOR_INTEL)
+	if (c->x86_vendor == X86_VENDOR_INTEL ||
+	    c->x86_vendor == X86_VENDOR_CENTAUR)
 		init_intel_pdc(pr, c);
 
 	return;