clocksource/drivers/sh_cmt: Add R-Car gen3 support

Add support for the R-Car gen3 CMT types 0/1 -- they seem to be the same
CMT types 0/1 as in R-Car gen2 SoCs.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>