ARM: multi_v7_defconfig: make eSDHC driver built-in

Sometimes root file system is deployed on SD card. It's
proper to build eSDHC driver into kernel.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>