mtd: correct typo "MTD_DATAFLASH_VERIFY_WRITE"

Fix the misspelling to match the actual config variable defined in
drivers/mtd/devi ces/Kconfig:

config MTD_DATAFLASH_WRITE_VERIFY
        bool "Verify DataFlash page writes"
        depends on MTD_DATAFLASH
Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/devices/mtd_dataflash.c

@@ -401,7 +401,7 @@ static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
 		(void) dataflash_waitready(priv->spi);
 
 
-#ifdef CONFIG_MTD_DATAFLASH_VERIFY_WRITE
+#ifdef CONFIG_MTD_DATAFLASH_WRITE_VERIFY
 
 		/* (3) Compare to Buffer1 */
 		addr = pageaddr << priv->page_offset;
@@ -430,7 +430,7 @@ static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
 		} else
 			status = 0;
 
-#endif	/* CONFIG_MTD_DATAFLASH_VERIFY_WRITE */
+#endif	/* CONFIG_MTD_DATAFLASH_WRITE_VERIFY */
 
 		remaining = remaining - writelen;
 		pageaddr++;