[ALSA] cmipci - Disable integrated mpu401 as default

Enable the support of mpu401 PCI port only when mpu_port=1 module
option is given, i.e. disabled as default.
It turned out that the check of integrated midi port isn't perfect
and caused hang-ups on some boards.

Signed-off-by: Takashi Iwai <tiwai@suse.de>