Enable 32 bit flash support for iMX21ADS board

The kernel configuration for the i.MX21ADS board (imx_v4_v5_defconfig)
doesn't enable 32 bit flash support. But the i.MX21ADS specific code
adds a 32 bit flash device, resulting in a kernel that refuses to
boot.
Signed-off-by: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/configs/imx_v4_v5_defconfig

@@ -67,7 +67,6 @@ CONFIG_MTD_CFI=y
 CONFIG_MTD_CFI_ADV_OPTIONS=y
 CONFIG_MTD_CFI_GEOMETRY=y
 # CONFIG_MTD_MAP_BANK_WIDTH_1 is not set
-# CONFIG_MTD_MAP_BANK_WIDTH_4 is not set
 # CONFIG_MTD_CFI_I2 is not set
 CONFIG_MTD_CFI_INTELEXT=y
 CONFIG_MTD_PHYSMAP=y