Bump buidlroot version to 2018.02.6

bsp/buildroot/support/scripts/apply-patches.sh

@@ -113,6 +113,11 @@ function apply_patch {
         echo "  to be applied  : ${path}/${patch}"
         exit 1
     fi
+    if grep -q "^rename from" ${path}/${patch} && \
+       grep -q "^rename to" ${path}/${patch} ; then
+        echo "Error: patch contains some renames, not supported by old patch versions"
+        exit 1
+    fi
     echo "${path}/${patch}" >> ${builddir}/.applied_patches_list
     ${uncomp} "${path}/$patch" | patch -g0 -p1 -E -d "${builddir}" -t -N $silent
     if [ $? != 0 ] ; then