x86/ioapic: Add register level checks to detect bogus io-apic entries

x86/ioapic: Add register level checks to detect bogus io-apic entries

With the recent changes to clear_IO_APIC_pin() which tries to
clear remoteIRR bit explicitly, some of the users started to see
"Unable to reset IRR for apic .." messages.

Close look shows that these are related to bogus IO-APIC entries
which returns all 1s for their io-apic registers. And the
above mentioned error messages are benign. But kernel should
have ignored such io-apic's in the first place.

Check if register 0, 1, 2 of the listed io-apic are all 1s and
ignore such io-apic.

[original Linux patch:]
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Jan Beulich <jbeulich@suse.com>