make local functions static and remove unused code

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

so we can dynamicly register the device

As we may need to use HW IP for clocksource.

As on EFI we could use Timestamp GUID if present (Not often the case as it's
not even enabled by default on any Target on EDK II not even OVMF)

Or if we choose we could use a Simulated Timestamp driver that work on Event
(Add Later)

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>