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/drivers/mtd/nand/raw/omap_gpmc.c b/drivers/mtd/nand/raw/omap_gpmc.c
index 97fd569..5305748 100644
--- a/drivers/mtd/nand/raw/omap_gpmc.c
+++ b/drivers/mtd/nand/raw/omap_gpmc.c
@@ -11,6 +11,7 @@
 #include <asm/arch/mem.h>
 #include <linux/mtd/omap_gpmc.h>
 #include <linux/mtd/nand_ecc.h>
+#include <linux/mtd/rawnand.h>
 #include <linux/bch.h>
 #include <linux/compiler.h>
 #include <nand.h>