Revert "bpf: add find_containing_subprog() utility function"

This reverts commit f0b56f1d which is
commit 27e88bc4 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I462f720ba02db62f4773863fd56cd7a360d15d88
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>