rockchip: lion-rk3368: defconfig: enable DM timer for all stages

There is no reasonably robust way (this will be needed so early that
diagnostics will be limited) to specify the base-address of the secure
timer through the DTS for TPL and SPL.  In order to allow us a cleaner
way to structure our SPL and TPL stage, we now move to a DM timer
driver.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>