console_simple: add fprintf / console_list for commands/loadb.c
commands/loadb.c doesn't build with CONFIG_CONSOLE_SIMPLE, because it uses
fprintf / for_each_console (which uses console_list).
Fix it by adding trivial implementations of both in console_simple.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>