net: ipa: derive channel from transaction

In gsi_channel_tx_queued(), we report when a transaction gets passed
to hardware.  Change that function so it takes transaction rather
than a channel as its argument, and derive the channel from the
transaction.  Rename the function accordingly.

Delete the header comments above the function definition; the ones
above the declaration in "gsi_private.h" should suffice.  In
addition, the comments above gsi_channel_tx_update() do a fine job
of explaining what's going on.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>