sf: Add QUAD_IO_FAST read support

This patch adds support QUAD_IO_FAST read command.

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index dca34f7..7be0292 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -45,6 +45,7 @@
 #define CMD_READ_DUAL_OUTPUT_FAST	0x3b
 #define CMD_READ_DUAL_IO_FAST		0xbb
 #define CMD_READ_QUAD_OUTPUT_FAST	0x6b
+#define CMD_READ_QUAD_IO_FAST		0xeb
 #define CMD_READ_ID			0x9f
 
 /* Bank addr access commands */