perf/x86: Disable uncore on virtualized CPUs

Initializing uncore PMU on virtualized CPU may hang the kernel.
This is because kvm does not emulate the entire hardware. Thers
are lots of uncore related MSRs, making kvm enumerate them all
is a non-trival task. So just disable uncore on virtualized CPU.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Tested-by: Pekka Enberg <penberg@kernel.org>
Cc: a.p.zijlstra@chello.nl
Cc: eranian@google.com
Cc: andi@firstfloor.org
Cc: avi@redhat.com
Link: http://lkml.kernel.org/r/1345540117-14164-1-git-send-email-zheng.z.yan@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>