mtd: spi-nor-core: Add support for volatile QE bit

Some of Spansion/Cypress chips support volatile version of configuration
registers and it is recommended to update volatile registers in the field
application due to a risk of the non-volatile registers corruption by
power interrupt. This patch adds a function to set Quad Enable bit in CFR1
volatile.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 5bb0688..81df05f 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -125,6 +125,7 @@
 #define SPINOR_OP_CLSR		0x30	/* Clear status register 1 */
 #define SPINOR_OP_RDAR		0x65	/* Read any register */
 #define SPINOR_OP_WRAR		0x71	/* Write any register */
+#define SPINOR_REG_ADDR_CFR1V	0x00800002
 
 /* Used for Micron flashes only. */
 #define SPINOR_OP_RD_EVCR	0x65	/* Read EVCR register */