Merge branch 'bpf-sockmap-fix-fionread-for-sockets-without-a-verdict-program'

Mattia Meleleo says:

====================
bpf, sockmap: Fix FIONREAD for sockets without a verdict program

Sockets added to a sockmap/sockhash with no stream/skb verdict program
attached answer FIONREAD with 0 even when unread data is pending in
sk_receive_queue. Fix tcp_bpf_ioctl() to account for the receive queue
in that case, and add a selftest.

Changes in v3:
- Remove unused sk_psock_msg_inq()
- Link to v2: https://patch.msgid.link/20260708-fionread-no-verdict-v2-0-29dd293621c7@coralogix.com

Changes in v2:
- Split the fix and the selftest into separate patches
- Use READ_ONCE() to read the verdict program pointers
- Link to v1: https://patch.msgid.link/20260707-fionread-no-verdict-v1-1-ce94a72357ec@coralogix.com

Signed-off-by: Mattia Meleleo <mattia.meleleo@coralogix.com>
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====================

Link: https://patch.msgid.link/20260708-fionread-no-verdict-v3-0-b4ee31b3af53@coralogix.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>