The drive/sample clocks can be phase shifted.  The drive clock
could be used in a future patch to adjust hold times.  The sample
clock is used for tuning.
Signed-off-by: NAlexandru M Stan <amstan@chromium.org>
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>