Add channel-gen.cpp to compilation units

The commit c01edf283dca792d1eecedd5c03b69b7eebb6f23 in
phosphor-host-ipmid had introduced a breaking change. This
commit would fix that.

Change-Id: Id3aa18bcc3b7f054b8c659916896de146064d8bb
Signed-off-by: Tom Joseph <tomjoseph@in.ibm.com>
2 files changed