ARM: imx_v6_v7_defconfig: Add support for framebuffer and camera on mx31

Let framebuffer and camera support be built by default on mx31.

Tested on a mx31pdk board.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>