uboot-imx

Set console speed to 115200 on mx6cuboxi.

By default, u-boot itself outputs on the serial console at 115200, so
it may as well pass the same value to the booted operating system as
well.

Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>