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>

include/exec/memory-internal.h

@@ -20,7 +20,7 @@
 #define MEMORY_INTERNAL_H
 
 #ifndef CONFIG_USER_ONLY
-#include "hw/xen.h"
+#include "hw/xen/xen.h"
 
 typedef struct PhysPageEntry PhysPageEntry;