Changed the message transmission logic about CA_DEFAULT_ADAPTER

Changed the message transmission logic about CA_DEFAULT_ADAPTER

if transport adapter type is set as CA_DEFAULT_ADAPTER,
CA transmit a message via all transport adapter after generating a pdu.
but CoAP over UDP and CoAP over TCP can be used to generating pdu
according to transport type. so transport type should be determined
before generating a pdu.

Change-Id: I1cd6adda7dd060239eb40d74c36a1fa69da619f5
Signed-off-by: hyuna0213.jo <hyuna0213.jo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/6115
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: jihwan seo <jihwan.seo@samsung.com>
Reviewed-by: Jon A. Cruz <jon@joncruz.org>