powerpc/perf_events: Fix priority of MSR HV vs PR bits

The architecture defines that if MSR PR is set we are in problem state
irrespective of the HV bit.  This fixes perf events to reflect this.

Also, on bare metal systems, samples taken in Linux will now be reported
as kernel rather than hypervisor.

Signed-off-by: Michael Neuling <mikey@neuling.org>
CC: paulus@samba.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>