Isolate Renesas R-Car Gen3 clock driver to R-Car Gen3 and Gen4 and RZ/G2L.
The Renesas R-Car Gen5 uses SCMI clock protocol driver instead. This is
a preparatory change for R-Car Gen5. No functional change.
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>