sunxi-configs: minimalize configs with savedefconfig

defconfig files should be saved with "make savedefconfig".

It has been fixed with this command:
>    for config in $(grep -rl 'Automatically generated' arch/arm/configs);
>    do
>        cp $config .config;
>        make ARCH=arm savedefconfig;
>        mv defconfig $config; rm .config;
>    done

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>