arm: mvebu: disable DEBUG_LL/EARLY_PRINTK in defconfig

Now that we have two different addresses for the UART, depending on
which bootloader is used, it is no longer desirable to enable
earlyprintk by default in the defconfig. Users who need earlyprintk
support will have to enable it explicitly, and select the right UART
configuration depending on their platform.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>