Clean up the C samples

Clean up the C samples

Update the URI in the samples for Unicast discovery and device discovery.

Change-Id: Ice2ec98bb33033743c17f3259e6a86380c0afc0e
Signed-off-by: Sakthivel Samidurai <sakthivel.samidurai@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/285
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>
Reviewed-by: Joseph Morrow <joseph.l.morrow@intel.com>
Reviewed-by: Yuliya Kamatkova <yuliya.kamatkova@intel.com>
Reviewed-by: Sudarshan Prasad <sudarshan.prasad@intel.com>