By passing the smd channel reference to the callback, rather than the
smd device, we can open additional smd channels from sub-devices of smd
devices.

Also updates the two smd clients today found in mainline.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NAndy Gross <andy.gross@linaro.org>