hw: move private headers to hw/ subdirectories.

Many headers are used only in a single directory.  These can be
kept in hw/.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
index 3ee2adf..01872db 100644
--- a/hw/xen/xen_pt_config_init.c
+++ b/hw/xen/xen_pt_config_init.c
@@ -14,7 +14,7 @@
 
 #include "qemu/timer.h"
 #include "hw/xen/xen_backend.h"
-#include "hw/xen_pt.h"
+#include "xen_pt.h"
 
 #define XEN_PT_MERGE_VALUE(value, data, val_mask) \
     (((value) & (val_mask)) | ((data) & ~(val_mask)))