powerpc/perf: Add thread IMC PMU support

powerpc/perf: Add thread IMC PMU support

BugLink: https://bugs.launchpad.net/bugs/1481347
Add support to register Thread In-Memory Collection PMU counters.
Patch adds thread IMC specific data structures, along with memory
init functions and CPU hotplug support.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry-picked from f74c89bd80fb3f1328fdf4a44eeba793cdce4222)
Signed-off-by: Gustavo Walbon <gwalbon@linux.vnet.ibm.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>