hw/clock: Let clock_set_mul_div() return a boolean value

hw/clock: Let clock_set_mul_div() return a boolean value

Let clock_set_mul_div() return a boolean value whether the
clock has been updated or not, similarly to clock_set().

Return early when clock_set_mul_div() is called with
same mul/div values the clock has.

Acked-by: Luc Michel <luc@lmichel.fr>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20240325152827.73817-2-philmd@linaro.org>