buildroot

apf27: update configuration

- move kernel 3.8.3 to 3.12.5
- enable pwm_imx in the kernel configuration
- add u-boot

Acked-by: Eric Jarrige <eric.jarrige@armadeus.org>
Acked-by: Julien Boibessot <julien.boibessot@armadeus.com>
Signed-off-by: Philippe Reynes <tremyfr@yahoo.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>