hotplug_mem: add hugepage test for ppc which default hugepage size is 16M

qemu/tests/cfg/hotplug_mem.cfg

@@ -68,12 +68,17 @@
             pre_command = "echo 3 > /proc/sys/vm/drop_caches"
             pre_command_noncritical = yes
             variants:
-                - @2M_hugepage:
+                - 2M_hugepage:
                     # default pagesize is 2M, 2G guest memory need to allocate
                     # in hugepage, so page nubmer is:
                     #    target_hugepages = (size_mem / page_size) * 2 + 10
+                    only i386, x86_64
                     target_hugepages = 2058
                     expected_hugepage_size = 2048
+                - 16M_hugepage:
+                    only pseries
+                    target_hugepages = 266
+                    expected_hugepage_size = 16384
                 - 1G_hugepage:
                     # Warning:
                     #     Please don't forget to update host kernel line to enable