vl: Eliminate usb_enabled()

This wrapper for machine_usb(current_machine) is not necessary,
replace all usages of usb_enabled() with machine_usb().

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: qemu-arm@nongnu.org
Cc: qemu-ppc@nongnu.org
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 1465419025-21519-3-git-send-email-ehabkost@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/hw/arm/realview.c b/hw/arm/realview.c
index 7d0aa6f..8eafcca 100644
--- a/hw/arm/realview.c
+++ b/hw/arm/realview.c
@@ -254,7 +254,7 @@
         sysbus_connect_irq(busdev, 2, pic[50]);
         sysbus_connect_irq(busdev, 3, pic[51]);
         pci_bus = (PCIBus *)qdev_get_child_bus(dev, "pci");
-        if (usb_enabled()) {
+        if (machine_usb(machine)) {
             pci_create_simple(pci_bus, -1, "pci-ohci");
         }
         n = drive_get_max_bus(IF_SCSI);