dfu: unify mmc/nand read/write ops enum

MMC and NAND independently defines same enumerators for read/write.
Unify them by defining enum in dfu header. RAM support that is being
added newly also can make use of it.

Signed-off-by: Afzal Mohammed <afzal.mohd.ma@gmail.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/dfu/dfu_nand.c b/drivers/dfu/dfu_nand.c
index 0ec12cf..edbf5a9 100644
--- a/drivers/dfu/dfu_nand.c
+++ b/drivers/dfu/dfu_nand.c
@@ -19,12 +19,7 @@
 #include <jffs2/load_kernel.h>
 #include <nand.h>
 
-enum dfu_nand_op {
-	DFU_OP_READ = 1,
-	DFU_OP_WRITE,
-};
-
-static int nand_block_op(enum dfu_nand_op op, struct dfu_entity *dfu,
+static int nand_block_op(enum dfu_op op, struct dfu_entity *dfu,
 			u64 offset, void *buf, long *len)
 {
 	loff_t start, lim;