rsi: fix occasional initialisation failure with BT coex

rsi: fix occasional initialisation failure with BT coex

commit 9b14ed6e11b72dd4806535449ca6c6962cb2369d upstream.

When BT coexistence is enabled (eg oper mode 13, which is the default)
the initialisation on startup sometimes silently fails.

In a normal initialisation we see
	usb 1-1.3: Product: Wireless USB Network Module
	usb 1-1.3: Manufacturer: Redpine Signals, Inc.
	usb 1-1.3: SerialNumber: 000000000001
	rsi_91x: rsi_probe: Initialized os intf ops
	rsi_91x: rsi_load_9116_firmware: Loading chunk 0
	rsi_91x: rsi_load_9116_firmware: Loading chunk 1
	rsi_91x: rsi_load_9116_firmware: Loading chunk 2
	rsi_91x: Max Stations Allowed = 1

But sometimes the last log is missing and the wlan net device is
not created.

Running a userspace loop that resets the hardware via a GPIO shows the
problem occurring ~5/100 resets.

The problem does not occur in oper mode 1 (wifi only).

Adding logs shows that the initialisation state machine requests a MAC
reset via rsi_send_reset_mac() but the firmware does not reply, leading
to the initialisation sequence being incomplete.

Fix this by delaying attaching the BT adapter until the wifi
initialisation has completed.

With this applied I have done > 300 reset loops with no errors.

Fixes: 716b840c7641 ("rsi: handle BT traffic in driver")
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
CC: stable@vger.kernel.org
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1630337206-12410-2-git-send-email-martin.fuzzey@flowbird.group
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>