virt: Fix broken indentation

I introduced indentation using tabs instead of spaces in another
commit.  Peter reported the problem, and I failed to fix that
before sending my pull request.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181212003147.29604-1-ehabkost@redhat.com
Fixes: 951597607696 ("virt: Eliminate separate instance_init functions")
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 17f1b49..5b67823 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1854,7 +1854,7 @@
     .instance_size = sizeof(VirtMachineState),
     .class_size    = sizeof(VirtMachineClass),
     .class_init    = virt_machine_class_init,
-	.instance_init = virt_instance_init,
+    .instance_init = virt_instance_init,
     .interfaces = (InterfaceInfo[]) {
          { TYPE_HOTPLUG_HANDLER },
          { }