x86, ioapic: Use snrpintf while set names for IO-APIC resourses

We should be ready that one day MAX_IO_APICS may raise its
number. To prevent memory overwrite we're to use safe
snprintf while set IO-APIC resourse name.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20091108155431.GC25940@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>