CA-98393/SCTX-1190: Prevent xal exception if console/vnc-port is missing.

Which can happen if disable_pv_vnc=true is specified in other-config.
This commit fixes the problem related to CA-90566.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
Merge pull request #1003 from jeromemaloberti/CA-98393-boston-lcm

CA-98393/SCTX-1190: Prevent xal exception if console/vnc-port is missing.