kvm: fix build error in ppc kvm due to memory_region_init_ram_ptr() change

Commit c5705a77 ("vmstate, memory: decouple vmstate from memory API") changed
the signature of memory_region_init_ram_ptr() but did not update a caller in
the ppc kvm module.  Fix.
Signed-off-by: NAvi Kivity <avi@redhat.com>

target-ppc/kvm.c

@@ -822,7 +822,8 @@ off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem)
     };
 
     rma_region = g_new(MemoryRegion, 1);
-    memory_region_init_ram_ptr(rma_region, NULL, name, size, rma);
+    memory_region_init_ram_ptr(rma_region, name, size, rma);
+    vmstate_register_ram_global(rma_region);
     memory_region_add_subregion(sysmem, 0, rma_region);
 
     return size;