clk: renesas: Split out code shared between Gen2 and Gen3

Pull code which is common for RCar Gen2 and RCar Gen3 into
separate source file. No functional change.

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