x86, apic: Limit apic dumping, introduce new show_lapic= setup option

In case if a system has a large number of cpus printing apics
contents may consume a long time period.

We limit such an output by 1 apic by default. But to have an
ability to see all apics or some part of them we introduce
"show_lapic" setup option which allow us to limit/unlimit the
number of APICs being dumped.

Example: apic=debug show_lapic=5, or apic=debug show_lapic=all

Also move apic_verbosity checking upper that way so helper routines
do not need to inspect it at all.

Suggested-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: yinghai@kernel.org
Cc: macro@linux-mips.org
LKML-Reference: <20091013201022.926793122@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>