debugtrace: use common output function

debugtrace: use common output function

Today dumping the debugtrace buffers is done via sercon_puts(), while
direct printing of trace entries (after toggling output to the console)
is using serial_puts().

Use sercon_puts() in both cases, as the difference between both is not
really making sense.

In order to prepare moving debugtrace functionality to an own source
file rename sercon_puts() to console_serial_puts() and make it globally
visible.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>