Delete commented code

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Use channel pan only without a master pan value

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Remove master pan effect and channel data

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[test] Add test for XM set pan effect

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>