Revert "bpf: fix null dereference when computing changes_pkt_data of prog w/o subprogs"

This reverts commit 3a467d93 which is
commit ac6542ad 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: If0aab3edf65fd03fb40a38f49a82f1775dfb9d1d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>