Fix Windows DUN error 619 caused by missing serial events and incorrect queue state

[5656hcx]

Summary

This change fixes multiple issues in the serial driver that caused Windows Dial‑Up Networking to fail with error 619.

Error Description

Repro: Initiate a dial-up connection against the Qualcomm modem on Windows Settings. The error 619 will pop up:

Root Cause Analysis (RCA)

1. Wrong output mask for WAIT_ON_MASK
   The driver completed IOCTL_SERIAL_WAIT_ON_MASK with an incorrect output event mask, so the application never observed SERIAL_EV_RXFLAG. As a result, the dial‑up flow could not proceed.

2. Queue state mis‑reporting rejected new WOM requests
   The logic used to determine whether the framework queue is empty was incorrect. Under certain race conditions, the application had already acknowledged the completion of the previous WAIT_ON_MASK request, but the driver still perceived the queue as non‑empty. As a result, the application restarted the connection by purging the RX buffer, which made all subsequent WAIT_ON_MASK requests were continuously rejected.

3. Potentially incorrect return status for immediate timeout
   Immediate timeout paths (Type 4/6) returned STATUS_TIMEOUT. The upper layer may interpreted this as a terminal failure.

Validation

Validated with Qualcomm modem on Windows 11 24h2, the error 619 is gone.