Fix: User commands require channel layer lib
Fix: User commands require channel layer lib

As channel layer is separated out from user layer lib, it
has to be manually included in libusercommands, as user
command handlers use channel layer API's

Tested-by:
1. Made sure that libusercommands are loaded on it's own
without any undefined symbol error.
2. ipmitool user list 1 works on host interface

Change-Id: I6652ad248e01afc1349e3a9612754dbdb84b96ad
Signed-off-by: Richard Marian Thomaiyar <72ed7ca0c1d67ded0b254900bd2112efa735a144@linux.intel.com>

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid