spapr: Make hash table size a factor of maxram_size

The hash table size is dependent on ram_size, but since with hotplug
the memory can grow till maxram_size. Hence make hash table size dependent
on maxram_size.

This allows to hotplug huge amounts of memory to the guest.
Signed-off-by: NBharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -1715,7 +1715,7 @@ static void ppc_spapr_init(MachineState *machine)
      * more than needed for the Linux guests we support. */
     spapr->htab_shift = 18; /* Minimum architected size */
     while (spapr->htab_shift <= 46) {
-        if ((1ULL << (spapr->htab_shift + 7)) >= machine->ram_size) {
+        if ((1ULL << (spapr->htab_shift + 7)) >= machine->maxram_size) {
             break;
         }
         spapr->htab_shift++;