When variable setup_console_atag is unset then read default value from OMAP
atags which passed NOLO bootloader to U-Boot.
This would allow to boot Maemo Linux kernel from U-Boot with serial console
settings configured in NOLO bootloader (which loads U-Boot).
So serial console needs to be enabled only at one place, globally in NOLO.
Signed-off-by: Pali Rohár <pali@kernel.org>
b5f7cf5017