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/hw/arm/gumstix.c b/hw/arm/gumstix.c
index 8859b73..4d800c9 100644
--- a/hw/arm/gumstix.c
+++ b/hw/arm/gumstix.c
@@ -35,10 +35,10 @@
  */
 
 #include "hw/hw.h"
-#include "hw/pxa.h"
+#include "hw/arm/pxa.h"
 #include "net/net.h"
-#include "hw/flash.h"
-#include "hw/devices.h"
+#include "hw/block/flash.h"
+#include "hw/arm/devices.h"
 #include "hw/boards.h"
 #include "sysemu/blockdev.h"
 #include "exec/address-spaces.h"