clk: starfive: Add StarFive JH7110 System-Top-Group clock driver

Add driver for the StarFive JH7110 System-Top-Group clock controller.

Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Hal Feng <hal.feng@starfivetech.com>
Co-developed-by: Xingyu Wu <xingyu.wu@starfivetech.com>
Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>