The stub is supposed to be there to bring up a CPU that needs to be
brought up because the platform requires so, but it needs to be as
practically quiet in terms of printing to the serial port as possible.
Thus, disable printing the boot banner by default.
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>