hw: move headers to include/

Many of these should be cleaned up with proper qdev-/QOM-ification.
Right now there are many catch-all headers in include/hw/ARCH depending
on cpu.h, and this makes it necessary to compile these files per-target.
However, fixing this does not belong in these patches.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/xen-all.c b/xen-all.c
index 8c05843..31f28fc 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -11,9 +11,9 @@
 #include <sys/mman.h>
 
 #include "hw/pci/pci.h"
-#include "hw/pc.h"
-#include "hw/xen_common.h"
-#include "hw/xen_backend.h"
+#include "hw/i386/pc.h"
+#include "hw/xen/xen_common.h"
+#include "hw/xen/xen_backend.h"
 #include "qmp-commands.h"
 
 #include "char/char.h"