staging: rtl8712: fix race condition

In probe function, request_firmware_nowait() is called to load firmware
asynchronously. At completion of firmware loading, register_netdev() is
called. However, a mutex needed by netdev is initialized after the call
to request_firmware_nowait(). Consequently, it can happen that
register_netdev() is called before the driver is ready.

Move the mutex initialization into r8712_init_drv_sw(), which is called
before request_firmware_nowait().

Reported-by: [e-mail]
Closes: https://lore.kernel.org/linux-staging/[e-mail]/T/#u
Fixes: 8c213fa59199 ("staging: r8712u: Use asynchronous firmware loading")
Cc: stable <[e-mail]>
Signed-off-by: Nam Cao <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/rtl8712/os_intfs.c

···
 	mp871xinit(padapter);
 	init_default_value(padapter);
 	r8712_InitSwLeds(padapter);
+	mutex_init(&padapter->mutex_start);
 
 	return 0;
 

drivers/staging/rtl8712/usb_intf.c

···
 	if (rtl871x_load_fw(padapter))
 		goto deinit_drv_sw;
 	init_completion(&padapter->rx_filter_ready);
-	mutex_init(&padapter->mutex_start);
 	return 0;
 
 deinit_drv_sw: