accel/ivpu: Fix VPU clock calculation

The driver calculates the wrong frequency because it ignores
the workpoint config and this cause undesired power/performance
characteristics. Fix this by using the workpoint config in
the freq calculations.

Fixes: 35b13763 ("accel/ivpu: Introduce a new DRM driver for Intel VPU")
Co-developed-by: Andrzej Kacprowski <andrzej.kacprowski@linux.intel.com>
Signed-off-by: Andrzej Kacprowski <andrzej.kacprowski@linux.intel.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323125504.2586442-8-stanislaw.gruszka@linux.intel.com