x86, smpboot: Remove unused variable

The cpuinfo_x86 ptr is unused now. Drop it. Got obsolete by 69fb3676


("x86 idle: remove mwait_idle() and "idle=mwait" cmdline param")
removing its only user.

[ hpa: fixes gcc warning ]

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1362428180-8865-2-git-send-email-bp@alien8.de
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>