minnowboard_max-graphical_defconfig: use uClibc-ng

Now that we have wordexp support in uClibc-ng and nodm is available, we can
use it for the graphical defconfig.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>