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/blockdev-nbd.c b/blockdev-nbd.c
index dc4e9a2..95f10c8 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -10,7 +10,7 @@
  */
 
 #include "sysemu/blockdev.h"
-#include "hw/block-common.h"
+#include "hw/block/block.h"
 #include "monitor/monitor.h"
 #include "qapi/qmp/qerror.h"
 #include "sysemu/sysemu.h"