[RI] Fix for out of memory issue in Arduino Mega

[RI] Fix for out of memory issue in Arduino Mega

OC log and OC log V used almost 3500bytes of RAM in Mega board because of improper log usage.
Updated code using PCF properly in OC logging to save almost 3500 bytes of RAM memory.

Verfied changes on both Arduino Due and Mega boards and found Working fine.

Change-Id: I9ca134d5cff9c8a91707a18bd9279089533a9b99
Signed-off-by: koushik.girijala <g.koushik@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2363
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Ashok Babu Channa <ashok.channa@samsung.com>
Reviewed-by: Abhishek Pandey <abhi.siso@samsung.com>
Reviewed-by: Jon A. Cruz <jonc@osg.samsung.com>