Removed warnings from calls to OC_LOG_BUFFER from within stack.

Removed warnings from calls to OC_LOG_BUFFER from within stack.

OC_LOG_BUFFER() expected "const uint8_t*" not "const unsigned char *".

Change-Id: I1e092abaf6af84ad66083c9bcf567d024e64b4d8
Signed-off-by: Joseph Morrow <joseph.l.morrow@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/290
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Yuliya Kamatkova <yuliya.kamatkova@intel.com>
Reviewed-by: Sashi Penta <sashi.kumar.penta@intel.com>
Reviewed-by: Sudarshan Prasad <sudarshan.prasad@intel.com>