[ALSA] cmipci: make the test for integrated MIDI port address more robust

Unused bytes in the I/O register range are likely to have the value 0x00
instead of 0xff, so test against both values when checking for the
presence of the integrated MIDI port.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>