net: tls: set MSG_SPLICE_PAGES consistently

We used to change the flags for the last segment, because
non-last segments had the MSG_SENDPAGE_NOTLAST flag set.
That flag is no longer a thing so remove the setting.

Since flags most likely don't have MSG_SPLICE_PAGES set
this avoids passing parts of the sg as splice and parts
as non-splice. Before commit under Fixes we'd have called
tcp_sendpage() which would add the MSG_SPLICE_PAGES.

Why this leads to trouble remains unclear but Tariq
reports hitting the WARN_ON(!sendpage_ok()) due to
page refcount of 0.

Fixes: e117dcf ("tls: Inline do_tcp_sendpages()")
Reported-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/all/4c49176f-147a-4283-f1b1-32aac7b4b996@gmail.com/
Tested-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20230808180917.1243540-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/tls/tls_main.c

@@ -139,9 +139,6 @@ int tls_push_sg(struct sock *sk,
 
 	ctx->splicing_pages = true;
 	while (1) {
-		if (sg_is_last(sg))
-			msg.msg_flags = flags;
-
 		/* is sending application-limited? */
 		tcp_rate_check_app_limited(sk);
 		p = sg_page(sg);