ARM: imx_v4_v5_defconfig: Select CONFIG_IMX_WEIM

The imx weim driver is used by some mx27/mx1 boards, so let's enable it by
default.

Generated this patch by doing:

- make imx_v4_v5_defconfig
- make menuconfig and manually select CONFIG_IMX_WEIM
- make savedefconfig
- cp defconfig arch/arm/configs/imx_v4_v5_defconfig

,which results in some additional cleanups.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>