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>
diff --git a/drivers/video/mali_dp.c b/drivers/video/mali_dp.c
index 71151a8..87a75a9 100644
--- a/drivers/video/mali_dp.c
+++ b/drivers/video/mali_dp.c
@@ -6,6 +6,7 @@
  */
 #define DEBUG
 #include <common.h>
+#include <malloc.h>
 #include <video.h>
 #include <dm.h>
 #ifdef CONFIG_DISPLAY
@@ -16,6 +17,7 @@
 #include <os.h>
 #include <fdt_support.h>
 #include <clk.h>
+#include <dm/device_compat.h>
 #include <linux/sizes.h>
 
 #define MALIDP_CORE_ID		0x0018