x86/apic: Prevent pointless warning messages

Markus reported that he sees new warnings:

  APIC: NR_CPUS/possible_cpus limit of 4 reached.  Processor 4/0x84 ignored.
  APIC: NR_CPUS/possible_cpus limit of 4 reached.  Processor 5/0x85 ignored.

This comes from the recent persistant cpuid - nodeid changes. The code
which emits the warning has been called prior to these changes only for
enabled processors. Now it's called for disabled processors as well to get
the possible cpu accounting correct. So if the kernel is compiled for the
number of actual available/enabled CPUs and the BIOS reports disabled CPUs
as well then the above warnings are printed.

That's a pointless exercise as it only makes sense if there are more CPUs
enabled than the kernel supports.

Nake the warning conditional on enabled processors so we are back to the
state before these changes.

Fixes: 8f54969dc8d6 ("x86/acpi: Introduce persistent storage for cpuid <-> apicid mapping") 
Reported-and-tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: linux-acpi@vger.kernel.org
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1610071549330.19804@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/apic.c

@@ -2128,9 +2128,11 @@ int __generic_processor_info(int apicid, int version, bool enabled)
 	if (num_processors >= nr_cpu_ids) {
 		int thiscpu = max + disabled_cpus;
 
-		pr_warning(
-			"APIC: NR_CPUS/possible_cpus limit of %i reached."
-			"  Processor %d/0x%x ignored.\n", max, thiscpu, apicid);
+		if (enabled) {
+			pr_warning("APIC: NR_CPUS/possible_cpus limit of %i "
+				   "reached. Processor %d/0x%x ignored.\n",
+				   max, thiscpu, apicid);
+		}
 
 		disabled_cpus++;
 		return -EINVAL;