[Task] UefiPxeBcDxe: Check return status of `NetLibDetectMediaWaitTimeout()` in

[makubacki]

The point of NetLibDetectMediaWaitTimeout() in DxeNetLib is to return whether network media is present. It returns a status code that is ignored in 14/15 calls throughout the codebase.

These are the possible return values defined for NetLibDetectMediaWaitTimeout():

mu_basecore/NetworkPkg/Library/DxeNetLib/DxeNetLib.c

Lines 2656 to 2687 in b09f1fd

	/**
	Detect media state for a network device. This routine will wait for a period of time at
	a specified checking interval when a certain network is under connecting until connection
	process finishs or timeout. If Aip protocol is supported by low layer drivers, three kinds
	of media states can be detected: EFI_SUCCESS, EFI_NOT_READY and EFI_NO_MEDIA, represents
	connected state, connecting state and no media state respectively. When function detects
	the current state is EFI_NOT_READY, it will loop to wait for next time's check until state
	turns to be EFI_SUCCESS or EFI_NO_MEDIA. If Aip protocol is not supported, function will
	call NetLibDetectMedia() and return state directly.
	@param[in] ServiceHandle The handle where network service binding protocols are
	installed on.
	@param[in] Timeout The maximum number of 100ns units to wait when network
	is connecting. Zero value means detect once and return
	immediately.
	@param[out] MediaState The pointer to the detected media state.
	@retval EFI_SUCCESS Media detection success.
	@retval EFI_INVALID_PARAMETER ServiceHandle is not a valid network device handle or
	MediaState pointer is NULL.
	@retval EFI_DEVICE_ERROR A device error occurred.
	@retval EFI_TIMEOUT Network is connecting but timeout.
	**/
	EFI_STATUS
	EFIAPI
	NetLibDetectMediaWaitTimeout (
	IN EFI_HANDLE ServiceHandle,
	IN UINT64 Timeout,
	OUT EFI_STATUS *MediaState
	)

It would be intuitive to expect that if NetLibDetectMediaWaitTimeout() returns a non-EFI_SUCCESS code, the output pointer value in the *MediaState argument is invalid. That's not done today.

---

This issue tracks exploration of conditionally accepting *MediaState in combination with the function return value. That may require other work like #1635 being completed first.

[makubacki]

I'll look into this after #1635 is complete. This is more of a correctness improvement on top of that.