ath10k: Fix the race condition in firmware dump work queue

There is a race condition, when the user writes 'hw-restart' and
'hard' in the simulate_fw_crash debugfs file without any delay.
In the above scenario, the firmware dump work queue(scheduled by
'hard') should be handled gracefully, while the target is in the
'hw-restart'.

Tested HW: QCA9984
Tested FW: 10.4-3.9.0.2-00044

Co-developed-by: Govindaraj Saminathan <gsamin@codeaurora.org>
Signed-off-by: Govindaraj Saminathan <gsamin@codeaurora.org>
Signed-off-by: Maharaja Kennadyrajan <mkenna@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1585213077-28439-1-git-send-email-mkenna@codeaurora.org