Add sanity check for LTS Kernel

layers/meta-belden-coreos/classes/coreos-sanity.bbclass

@@ -29,5 +29,13 @@ python check_coreos_sanity_eventhandler() {
             "Using glibc is mandatory on CoreOS based distribution"
         )
 
+    virtKernel = e.data.getVar('PREFERRED_PROVIDER_virtual/kernel')
+    if "lts" not in virtKernel:
+        bb.warn(
+            "No LTS Linux Kernel used. "
+            "It is highly recommended to use a LTS version. "
+            "Currently used provider is: %s_%s" % (virtKernel, e.data.getVar('PREFERRED_VERSION_' + virtKernel))
+        )
+
     return
 }