README: Remove CONFIG_SPI_FLASH_DATAFLASH help text

Since the help text is added in drivers/mtd/spi/Kconfig

Signed-off-by: Jagan Teki <jteki@openedev.com>

README

@@ -3085,11 +3085,6 @@ CBFS (Coreboot Filesystem) support
 		memories can be connected with a given cs line.
 		Currently Xilinx Zynq qspi supports these type of connections.
 
-		CONFIG_SPI_FLASH_DATAFLASH	SPI based Dataflash
-
-		Define this option to access AT45xxx Dataflash chips support
-		using spi flash interface.
-
 - SystemACE Support:
 		CONFIG_SYSTEMACE