configs: Add Freescale MX53 support

Buildroot config and Linux Kernel config.
Freescale binaries (xf86 video driver and multimedia codecs) not supported yet.

Signed-off-by: Mathieu Briand <mbriand@adeneo-embedded.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>