target/riscv: Have kvm_riscv_get_timebase_frequency() take RISCVCPU cpu

target/riscv: Have kvm_riscv_get_timebase_frequency() take RISCVCPU cpu

Keep kvm_riscv_get_timebase_frequency() prototype aligned with
the other ones declared in "kvm_riscv.h", have it take a RISCVCPU
cpu as argument. Include "target/riscv/cpu-qom.h" which declares
the RISCVCPU typedef.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250112231344.34632-2-philmd@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>