clocksource/drivers/sh_cmt: Support separate R-Car Gen2 CMT0/1

Add support for the new R-Car Gen2 CMT0 and CMT1 bindings. Support
for the old DT binding is still kept around, however devices using
such binding will be treated as a low-feature CMT0 device. If users
want to make use of CMT1-specific features then they need to update
their DTBs. No special CMT1-specific features are however implemented
by his patch, only DT bindings are redone as groundwork for future
feature patches.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>