Revert "net:bluetooth:l2 cap core GCC 4.8 patch"

This reverts commit 94a892933edcf35272a77bb11c2a9536c65270a0.
Revert "Make kernel compatible with gcc <=4.8"

This reverts commit 5109a041fcd29c08974668e8579c4e55f33c5f5a.