Revert "bpf: consider that tail calls invalidate packet pointers"

This reverts commit f1692ee23d which is
commit 1a4607ffba35bf2a630aab299e34dd3f6e658d70 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: Ie3fb4b43ba1abcbc9f7977c54c8fed847f7455c7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

net/core/filter.c

@@ -7911,8 +7911,6 @@ bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id)
 	case BPF_FUNC_xdp_adjust_head:
 	case BPF_FUNC_xdp_adjust_meta:
 	case BPF_FUNC_xdp_adjust_tail:
-	/* tail-called program could call any of the above */
-	case BPF_FUNC_tail_call:
 		return true;
 	default:
 		return false;