nand: Drop dm.h header file

This header file should not be included in other header files. Remove it
and use a forward declaration instead.

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

drivers/mtd/nand/raw/brcmnand/brcmnand_compat.c

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0+
 
 #include <common.h>
+#include <dm.h>
 #include <malloc.h>
 #include <dm/devres.h>
 #include "brcmnand_compat.h"

drivers/mtd/nand/raw/brcmnand/brcmnand_compat.h

@@ -3,8 +3,8 @@
 #ifndef __BRCMNAND_COMPAT_H
 #define __BRCMNAND_COMPAT_H
 
-#include <clk.h>
-#include <dm.h>
+struct clk;
+struct udevice;
 
 char *devm_kasprintf(struct udevice *dev, gfp_t gfp, const char *fmt, ...);