Add timer driver in Starfive SoC. It is an timer that outside
of CPU core and inside Starfive SoC.

Signed-off-by: Kuan Lim Lee <kuanlim.lee@starfivetech.com>
Reviewed-by: Wei Liang Lim <weiliang.lim@starfivetech.com>
Reviewed-by: Simon Glass <sjg@chromium.org>