Bluetooth: btintel_pcie: split coredump worker into per-trigger works

btintel_pcie_coredump_worker() handled three unrelated jobs in one
work item: collect a DRAM trace coredump, read the hardware exception
event, and read the firmware-trigger event. The worker walked three
flag bits at runtime and each interrupt path mutated multiple bits
to communicate which sub-jobs the worker should run, which made the
ownership rules for those bits hard to reason about and entangled
the trigger reason with the in-progress accounting.

Replace the single combined worker with three single-purpose ones,
each owning exactly one flag:

  coredump_work    -> btintel_pcie_dump_traces()
                      guarded by COREDUMP_INPROGRESS
  hwexp_work       -> btintel_pcie_read_hwexp()
                      guarded by CORE_HALTED (already permanent until
                      re-probe; HWEXP_INPROGRESS is now redundant
                      and removed)
  fwtrigger_work   -> btintel_pcie_dump_fwtrigger_event()
                      guarded by FWTRIGGER_DUMP_INPROGRESS

All three workers are queued on a shared ordered workqueue (renamed
coredump_workqueue -> dump_workqueue) so a companion event reader
(hwexp/fwtrigger) and the coredump always run FIFO. Companion work
is queued before coredump_work so dmp_hdr.event_type/event_id are
populated by the time dump_traces() consumes them, preserving the
original ordering.

Introduce btintel_pcie_queue_coredump() to centralize the coredump
trigger contract: it is the single writer of COREDUMP_INPROGRESS and
of dmp_hdr.trigger_reason, sets both atomically against concurrent
triggers, and rolls back the bit if the workqueue is disabled
(reset/remove in progress) so a later trigger after re-probe can
succeed. All four trigger sites (HWEXP IRQ, FW-trigger IRQ,
devcoredump user trigger, resume() D0 error path) go through the
helper.

Per-work guard bits are now cleared at the tail of each worker
rather than in the middle of the combined worker, which closes a
subtle race where a duplicate IRQ could observe a cleared bit and
requeue while the previous pass was still finalizing
dev_coredumpv().

reset_work() and remove() now disable_work_sync() all three workers
and, on the FLR-failure path, enable_work() all three to keep their
disable counters balanced. The PLDR/FLR-success contract (re-probe
re-INIT_WORKs everything with counter 0) is preserved.

No functional change to the dump payloads; this is a pure
restructuring of the worker dispatch and its synchronization.

Signed-off-by: Kiran K <kiran.k@intel.com>
Assisted-by: GitHub-Copilot:claude-4.7-opus
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>