Blackfin arch: Print out debug info, as early as possible

Blackfin arch: Print out debug info, as early as possible

Print out debug info, as early as possible - even before the
kernel initializes the interrupt vectors. Now we can print out debug
messages almost anytime during the boot process.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>