Impact: fix /proc/cpuinfo output on x86/Voyager

Ever since

| commit 92cb7612
| Author: Mike Travis <travis@sgi.com>
| Date:   Fri Oct 19 20:35:04 2007 +0200
|
|     x86: convert cpuinfo_x86 array to a per_cpu array

We've had an extra field in cpuinfo_x86 which is cpu_index.
Unfortunately, voyager has never initialised this, although the only
noticeable impact seems to be that /proc/cpuinfo shows all zeros for
the processor ids.

Anyway, fix this by initialising the boot CPU properly and setting the
index when the secondaries update.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>