amidi: restore space between bytes

amidi: restore space between bytes

Commit 9a8fcec ("amidi: add timestamp option for dump") removed the
space between bytes when dumping MIDI, changing the output from:

	90 45 40
	80 45 00

to:

	904540
	804500

It seems that this was an unintentional side effect of refactoring the
code to add the new timestamp output but the result is less readable
than it was before.

Restore the space between bytes in the same message.

Fixes: 9a8fcec ("amidi: add timestamp option for dump")
Fixes: https://github.com/alsa-project/alsa-utils/pull/158/
Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>