fix(emqx_lwm2m): bump to lwm2m_coap 1.1.2

apps/emqx_lwm2m/rebar.config

@@ -1,5 +1,5 @@
 {deps,
- [{lwm2m_coap, {git, "https://github.com/emqx/lwm2m-coap", {tag, "v1.1.1"}}}
+ [{lwm2m_coap, {git, "https://github.com/emqx/lwm2m-coap", {tag, "v1.1.2"}}}
  ]}.
 
 {profiles,