x86: io-apic: IO-APIC MMIO should not fail on resource insertion

If IO-APIC base address is 1K aligned we should not fail
on resourse insertion procedure. For this sake we define
IO_APIC_SLOT_SIZE constant which should cover all IO-APIC
direct accessible registers.

An example of a such configuration is there

	http://marc.info/?l=linux-kernel&m=118114792006520

 |
 | Quoting the message
 |
 | IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23
 | IOAPIC[1]: apic_id 3, version 32, address 0xfec80000, GSI 24-47
 | IOAPIC[2]: apic_id 4, version 32, address 0xfec80400, GSI 48-71
 | IOAPIC[3]: apic_id 5, version 32, address 0xfec84000, GSI 72-95
 | IOAPIC[4]: apic_id 8, version 32, address 0xfec84400, GSI 96-119
 |

Reported-by: "Maciej W. Rozycki" <macro@linux-mips.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20091116151426.GC5653@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>