ARM: imx: udoo: drop MTD config

The UDOO doesn't have any MTD storage so drop the config.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>

configs/udoo_defconfig

@@ -42,7 +42,6 @@ CONFIG_DWC_AHSATA=y
 CONFIG_FSL_USDHC=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y
-CONFIG_MTD=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
 CONFIG_PHY_MICREL_KSZ90X1=y