clk: rmobile: Add RCar Gen3 clock driver

Add clock driver for the RCar Gen3 R8A7795 and R8A7796 SoCs .
This driver allows reading out the clock configuration set by
previous boot stages and enabling and disabling clock using
the MSTP registers. Setting clock is not supported thus far.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
5 files changed