drivers: clock: rcar: Add r8a779f0 support

Add support of r8a779f0 cpg driver.
r8a779f0 soc has its own clock tree.
Gen4 SoCs common registers addresses have been added in header.

Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
Signed-off-by: Aymeric Aillet <aymeric.aillet@iot.bzh>