ARM: imx_v6_v7_defconfig: Select the coda driver as module

The coda driver may be probed prior to the rootfs being available, leading
to firmware loading failure.

To avoid such problem, select the coda driver as module.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>