Add the capability to trigger deferred error interrupts and
threshold interrupts in order to test the APIC interrupt handler
functionality for these type of errors.

Update README section about the same too.

Reported by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
[ Cleanup comments. ]
[ Include asm/irq_vectors.h directly so that misc randbuilds don't fail. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1443190851-2172-3-git-send-email-Aravind.Gopalakrishnan@amd.com
Link: http://lkml.kernel.org/r/1444641762-9437-4-git-send-email-bp@alien8.deSigned-off-by: Ingo Molnar <mingo@kernel.org>