ARM: mx31moboard-smartbot: Remove camera support

Since commit c93cc614 ("[media] staging/media: remove deprecated
mx3 driver") the mx3 camera driver has been removed, so remove the camera
support from the board file as well.

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