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

This reverts commit f0946dcc 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: I118af20de9e39a79659ec9d336a807f7c05a3411
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>