Midi input via JACK works only through channel 1

Commit 1514034.

Steps to reproduce:
1. Open MuseScore, enable midi input via JACK.
2. Connect your midi device, set it's channel to 1 < N < 16
3. Click somewhere on the staff, press "N", 7 and a key on your midi device.

Expected result: a new note should appear on the staff.
Actual result: nothing happens.

Midi input works only if midi device's channel is 1.