ARM: mxs: Update mxs_defconfig

Regenerate the mxs_defconfig to match recent kernel using the following
commands:

make mxs_defconfig
make savedefconfig
cp defconfig arch/arm/configs/mxs_defconfig

Then enable these features:
- MTD block access
- UBI and UBIFS
- JFFS2
- EXT2 and EXT4
- AT24 EEPROM support
- Support for most of the SPI flashes
- Support for ethernet PHYs that are usually used on mxs designs

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>