powerpc/perf/imc: Use cpu_to_node() not topology_physical_package_id()

powerpc/perf/imc: Use cpu_to_node() not topology_physical_package_id()

init_imc_pmu() uses topology_physical_package_id() to detect the
node id of the processor it is on to get local memory, but that's
wrong, and can lead to crashes. Fix it to use cpu_to_node().

Fixes: 885dcd709ba9 ("powerpc/perf: Add nest IMC PMU support")
Cc: [email protected] # v4.14+
Reported-By: Rob Lippert <[email protected]>
Tested-By: Madhavan Srinivasan <[email protected]>
Signed-off-by: Madhavan Srinivasan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>