Client drivers such as the ChomeOS EC driver sometimes use transfers with
no buffers and only a delay specified in order to allow a delay after the
assertion of /CS. Rather than require controller drivers handle this noop
case gracefully put checks in the core to ensure that we don't call into
the controller for such transfers.
Reported-by: NAddy Ke <addy.ke@rock-chips.com>
Tested-by: NDoug Anderson <dianders@chromium.org>
Reviewed-by: NDoug Anderson <dianders@chromium.org>
Signed-off-by: NMark Brown <broonie@linaro.org>