rtw88: refine fw_crash debugfs to show non-zero while triggering

rtw88: refine fw_crash debugfs to show non-zero while triggering

The usage of fw_crash debugfs is to write 1 to it to trigger fw crash
simulation and to read from it to check the state. When zero is read,
it is supposed to mean fw crash/restart process is done. Then, some
test plans can be designed for crash/restart.
e.g.
step 1. trigger fw crash simulation
step 2. poll the state until zero is read
step 3. check connection by ping test

However, in certain connection cases, triggering fw crash simulation
will take a while. If the state is queried too early before restart
begins processing, it may mistakenly think restart process has been
done. If some tests are started at this time, something unexpected
might happen due to the follow-up restart process.

To avoid that, let fw_crash also show non-zero when a simulation
is still triggering.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211001082301.4805-1-pkshih@realtek.com