clk: starfive: Add StarFive JH7110 system clock driver

Add driver for the StarFive JH7110 system clock controller and
register an auxiliary device for system reset controller which
is named as "rst-sys".

Tested-by: Tommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Co-developed-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>