hw/ppc: modified the condition for usb controllers to be created for some ppc machines

Some ppc machines create a default usb controller based on a 'machine condition'.
Until now the logic was: create the usb controller if:
 -  the usb option was supplied in cli and value is true or
 -  the usb option was absent and both set_defaults and the machine
    condition were true.

Modified the logic to:
Create the usb controller if:
 - the machine condition is true and defaults are enabled or
 - the usb option is supplied and true.

The main for this is to simplify the usb_enabled method.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/ppc/mac_newworld.c

@@ -417,7 +417,8 @@ static void ppc_core99_init(MachineState *machine)
     dev = qdev_create(adb_bus, TYPE_ADB_MOUSE);
     qdev_init_nofail(dev);
 
-    if (usb_enabled(machine_arch == ARCH_MAC99_U3)) {
+    if ((machine_arch == ARCH_MAC99_U3 && defaults_enabled()) ||
+        usb_enabled(false)) {
         pci_create_simple(pci_bus, -1, "pci-ohci");
         /* U3 needs to use USB for input because Linux doesn't support via-cuda
         on PPC64 */

hw/ppc/spapr.c

@@ -1530,7 +1530,7 @@ static void ppc_spapr_init(MachineState *machine)
         spapr->has_graphics = true;
     }
 
-    if (usb_enabled(spapr->has_graphics)) {
+    if ((spapr->has_graphics && defaults_enabled()) || usb_enabled(false)) {
         pci_create_simple(phb->bus, -1, "pci-ohci");
         if (spapr->has_graphics) {
             usbdevice_create("keyboard");

include/sysemu/sysemu.h

@@ -227,6 +227,7 @@ void qemu_boot_set(const char *boot_order, Error **errp);
 
 QemuOpts *qemu_get_machine_opts(void);
 
+bool defaults_enabled(void);
 bool usb_enabled(bool default_usb);
 
 extern QemuOptsList qemu_legacy_drive_opts;

vl.c

@@ -997,10 +997,15 @@ static int parse_name(QemuOpts *opts, void *opaque)
     return 0;
 }
 
+bool defaults_enabled(void)
+{
+    return has_defaults;
+}
+
 bool usb_enabled(bool default_usb)
 {
     return qemu_opt_get_bool(qemu_get_machine_opts(), "usb",
-                             has_defaults && default_usb);
+                             default_usb);
 }
 
 #ifndef _WIN32