virtio-serial: Fix compat property name

Starting with qemu -M pc-0.12 -device virtio-serial

results in

-device virtio-serial: Property 'virtio-serial-pci.max_nr_ports' not found

The property name 'max_ports' is incorrectly named 'max_nr_ports'. Fix
that.

Also fix the ppc440 machine type bamboo-0.12 which has this typo.
Reported-by: NDaniel P. Berrange <berrange@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

hw/pc_piix.c

@@ -226,7 +226,7 @@ static QEMUMachine pc_machine_v0_12 = {
     .compat_props = (GlobalProperty[]) {
         {
             .driver   = "virtio-serial-pci",
-            .property = "max_nr_ports",
+            .property = "max_ports",
             .value    = stringify(1),
         },{
             .driver   = "virtio-serial-pci",
@@ -249,7 +249,7 @@ static QEMUMachine pc_machine_v0_11 = {
             .value    = stringify(0),
         },{
             .driver   = "virtio-serial-pci",
-            .property = "max_nr_ports",
+            .property = "max_ports",
             .value    = stringify(1),
         },{
             .driver   = "virtio-serial-pci",
@@ -288,7 +288,7 @@ static QEMUMachine pc_machine_v0_10 = {
             .value    = stringify(PCI_CLASS_DISPLAY_OTHER),
         },{
             .driver   = "virtio-serial-pci",
-            .property = "max_nr_ports",
+            .property = "max_ports",
             .value    = stringify(1),
         },{
             .driver   = "virtio-serial-pci",

hw/ppc440_bamboo.c

@@ -186,7 +186,7 @@ static QEMUMachine bamboo_machine_v0_12 = {
     .compat_props = (GlobalProperty[]) {
         {
             .driver   = "virtio-serial-pci",
-            .property = "max_nr_ports",
+            .property = "max_ports",
             .value    = stringify(1),
         },{
             .driver   = "virtio-serial-pci",