arm: fix location of some include files

The recent rearrangement of include files had some minor errors:
 devices.h is not ARM specific and should not be in arm/
 arm.h should be in arm/

Move these two headers to correct this.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/microblaze/petalogix_s3adsp1800_mmu.c b/hw/microblaze/petalogix_s3adsp1800_mmu.c
index eedd60e..7c258f0 100644
--- a/hw/microblaze/petalogix_s3adsp1800_mmu.c
+++ b/hw/microblaze/petalogix_s3adsp1800_mmu.c
@@ -28,7 +28,7 @@
 #include "net/net.h"
 #include "hw/block/flash.h"
 #include "sysemu/sysemu.h"
-#include "hw/arm/devices.h"
+#include "hw/devices.h"
 #include "hw/boards.h"
 #include "hw/xilinx.h"
 #include "sysemu/blockdev.h"