Merge branch 'sctp-fix-a-null-pointer-dereference-in-sctp_sched_dequeue_common'

Merge branch 'sctp-fix-a-null-pointer-dereference-in-sctp_sched_dequeue_common'

Xin Long says:

====================
sctp: fix a NULL pointer dereference in sctp_sched_dequeue_common

This issue was triggered with SCTP_PR_SCTP_PRIO in sctp,
and caused by not checking and fixing stream->out_curr
after removing a chunk from this stream.

Patch 1 removes an unnecessary check and makes the real
fix easier to add in Patch 2.
====================

Link: https://lore.kernel.org/r/cover.1667598261.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>