mtd: spi-nor: fix the wrong dummy value

For the DDR Quad read, the dummy cycles maybe 3 or 6 which is less then 8.
The dummy cycles is actually 8 for SPI fast/dual/quad read.

This patch makes preparations for the DDR quad read, it fixes the wrong dummy
value for both the spi-nor.c and m25p80.c.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index ed827cf..5d44825 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -128,9 +128,12 @@
 	struct spi_device *spi = flash->spi;
 	struct spi_transfer t[2];
 	struct spi_message m;
-	int dummy = nor->read_dummy;
+	unsigned int dummy = nor->read_dummy;
 	int ret;
 
+	/* convert the dummy cycles to the number of bytes */
+	dummy /= 8;
+
 	/* Wait till previous write/erase is done. */
 	ret = nor->wait_till_ready(nor);
 	if (ret)
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index a98c134..ea6516d 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -98,7 +98,7 @@
 	case SPI_NOR_FAST:
 	case SPI_NOR_DUAL:
 	case SPI_NOR_QUAD:
-		return 1;
+		return 8;
 	case SPI_NOR_NORMAL:
 		return 0;
 	}