RFC: completion: support poll()

[Ramon Fried]

Hi.
If what I'm suggesting makes no sense please tell me. :)

In a char driver I'm writing I'm using completion to wait for transmit
operation to complete.
The drivers also exposes poll() functionality to wait for transmission
to complete.

poll_wait() requires a wait queue, is there a reason why can't I use
the wait queue that is hidden inside the completion struct ?

I'm suggesting to add an API to get the wait_queue so it can be used
for the above scenario.

Appreciate your comments.
Thanks,
Ramon.