nand.h: Cleanup linux/mtd/rawnand.h usage

We only include <linux/mtd/rawnand.h> in <nand.h> for the forward
declaration of struct nand_chip, so do that directly.  Then, include
<linux/mtd/rawnand.h> where required directly.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/nand.c b/cmd/nand.c
index d381053..df5a4b1 100644
--- a/cmd/nand.c
+++ b/cmd/nand.c
@@ -24,6 +24,7 @@
 #include <image.h>
 #include <asm/cache.h>
 #include <linux/mtd/mtd.h>
+#include <linux/mtd/rawnand.h>
 #include <command.h>
 #include <console.h>
 #include <env.h>