qemu: Remove useless ARCH_IS_X86() call

Now that we have added architecture checks to all
qemuDomainIs*() functions, we no longer need to perform the
same checks separately.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>

src/qemu/qemu_domain.c

@@ -7783,7 +7783,7 @@ qemuDomainDefFormatBufInternal(virQEMUDriverPtr driver,
          * because other architectures and machine types were introduced
          * when libvirt already supported <controller type='usb'/>.
          */
-        if (ARCH_IS_X86(def->os.arch) && qemuDomainIsI440FX(def) &&
+        if (qemuDomainIsI440FX(def) &&
             usb && usb->idx == 0 &&
             (usb->model == VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT ||
              usb->model == VIR_DOMAIN_CONTROLLER_MODEL_USB_PIIX3_UHCI) &&