ALSA: hdspm - Fix midi port initialization

Depending on the model and the presence of a TCO module, the number of
midi ports varies. Some have 1 port (MADIface), some have 2 (default),
with TCO, there are 3.

Don't hardcode the number of midi ports to initialize.

This patch also fixes a boot lockup on MADIface.

[Coding-style fixes by tiwai]

Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>