x86, apic: Print verbose error interrupt reason on apic=debug

x86, apic: Print verbose error interrupt reason on apic=debug

End users worry about the error interrupt printout we generate
currently:

	pr_debug("APIC error on CPU%d: %02x(%02x)\n",
	smp_processor_id(), v , v1);

... and would like to know the reason why error interrupts are generated.

This patch prints out more detailed debug information.

Another practical problem is that dynamic debug is not initialized yet
when the APIC initializes, so the pr_debug() will not output the error
interrupt debug information on bootup. In this patch, we use
apic_printk(APIC_DEBUG, ...), so the apic=debug boot option will print
verbose error interupts during bootup.

Signed-off-by: Youquan Song <youquan.song@intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: hpa@linux.intel.com
Cc: suresh.b.siddha@intel.com
Cc: yong.y.wang@linux.intel.com
Cc: jbaron@redhat.com
Cc: trenn@suse.de
Cc: kent.liu@intel.com
Cc: chaohong.guo@intel.com
Link: http://lkml.kernel.org/r/1302762968-24380-2-git-send-email-youquan.song@intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>