Added const keyword to several function parameters.

Added const keyword to several function parameters.

This file was considered in need of re-examination with regards to making
parameters const "where necessary" during the RI Code Review process (be-
fore merging the connectivity-abstraction and master branch).

Change-Id: I12db60e5404a0a5ce7811d53efc637815160a012
Signed-off-by: Joseph Morrow <joseph.l.morrow@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/540
Reviewed-by: Sakthivel Samidurai <sakthivel.samidurai@intel.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Erich Keane <erich.keane@intel.com>