dm: core: Create a new header file for 'compat' features

At present dm/device.h includes the linux-compatible features. This
requires including linux/compat.h which in turn includes a lot of headers.
One of these is malloc.h which we thus end up including in every file in
U-Boot. Apart from the inefficiency of this, it is problematic for sandbox
which needs to use the system malloc() in some files.

Move the compatibility features into a separate header file.

Signed-off-by: Simon Glass <sjg@chromium.org>

lib/libavb/avb_rsa.c

@@ -12,6 +12,7 @@
 #include "avb_sha.h"
 #include "avb_util.h"
 #include "avb_vbmeta_image.h"
+#include <malloc.h>
 
 typedef struct IAvbKey {
   unsigned int len; /* Length of n[] in number of uint32_t */