wifi: rtw89: debug: support SER L0 simulation

SER (system error recovery) can deal with different crash types by
different levels of processes. Now, add a debug function to trigger
MAC error in purpose for SER L0 simulation/verification. And, extend
dbgfs fw_crash to accept different parameters.

    # simulate MAC error (one kind of SER L0)
    echo 3 > fw_crash

Normally, FW won't report SER L0 cases to driver. Instead, they will
be handled by FW directly. If unfortunately FW handling fails, SER
will rise to L1 and be reported to driver.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250915065329.38911-1-pkshih@realtek.com