amiserial: remove unused DBG_CNT

The ugly DBG_CNT macro is unused, so remove.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210714091314.8292-1-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>