CoAP library is migrated to support over socket based
applications or other higher layer protocols. Most of the
API's and functionality is kept as it is except few changes.
net_pkt/net_buf is removed from CoAP library. Now it expects
a pre-allocated flat buffer and length. If there is not enough
space to append any data, library simply returns an error.
It's user's responsibility to allocate and free memory.
One change in functionality is, earlier coap_pending_clear()
used to clear the memory, but now it's user's responsibility
to free the memory.
Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>