x86: Fix and clean up generic_processor_info()

One of the error printouts in generic_processor_info() prints out
the APIC version instead of the cpu index the warning text describes.

Move version validation down, after we get the right cpu index.

-v2: add comments about reason why we can have cpu=0 there.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4D5240A9.4080703@kernel.org>
[ Cleaned up and made the BIOS bug printouts more consistent ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>