accel/ivpu: Read clock rate only if device is up

Do not unnecessarily wake up device to read clock rate.
Return 0 as clk_rate if device is suspended.

Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231020104501.697763-4-stanislaw.gruszka@linux.intel.com