Convert CONFIG_SYS_FLASH_CFI_WIDTH to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FLASH_CFI_WIDTH

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/M5235EVB_defconfig b/configs/M5235EVB_defconfig
index fed386c..5eeed2d 100644
--- a/configs/M5235EVB_defconfig
+++ b/configs/M5235EVB_defconfig
@@ -41,6 +41,7 @@
 CONFIG_SYS_I2C_SPEED=80000
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y
+CONFIG_SYS_FLASH_CFI_WIDTH_16BIT=y
 CONFIG_SYS_FLASH_PROTECTION=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_DM_ETH=y