nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path

nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path

In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected,
nvmet_req_uninit() is called unconditionally. However, if the command
arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init()
had returned false and percpu_ref_tryget_live() was never executed. The
unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a
refcount underflow, leading to a WARNING in
percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and
eventually a permanent workqueue deadlock.

Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling
nvmet_req_uninit(), matching the existing pattern in
nvmet_tcp_execute_request().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Shivam Kumar <kumar.shivam43666@gmail.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>