There are three users of at91_dbgu_setup_ll and all already call this
function only when IS_ENABLED(CONFIG_DEBUG_LL). Remove the duplicated
condition from the function itself. This allows us to use the function
for pbl_set_console use later on, even with DEBUG_LL disabled.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>