mtd: spi-nor-core: Add octal mode support

Add support for Octal flash devices. Octal flash devices use 8 IO lines
for data transfer. Currently only 1-1-8 Octal Read mode is supported.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/include/spi.h b/include/spi.h
index 18a0312..852f570 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -30,6 +30,8 @@
 #define SPI_RX_SLOW	BIT(11)			/* receive with 1 wire slow */
 #define SPI_RX_DUAL	BIT(12)			/* receive with 2 wires */
 #define SPI_RX_QUAD	BIT(13)			/* receive with 4 wires */
+#define SPI_TX_OCTAL	BIT(14)			/* transmit with 8 wires */
+#define SPI_RX_OCTAL	BIT(15)			/* receive with 8 wires */
 
 /* Header byte that marks the start of the message */
 #define SPI_PREAMBLE_END_BYTE	0xec