accel/ivpu: Fix the NPU's DPU frequency calculation

Fix the frequency returned to the user space by
the DRM_IVPU_PARAM_CORE_CLOCK_RATE GET_PARAM IOCTL.
The kernel driver returned CPU frequency for MTL and bare
PLL frequency for LNL - this was inconsistent and incorrect
for both platforms. With this fix the driver returns maximum
frequency of the NPU data processing unit (DPU) for all HW
generations. This is what user space always expected.

Also do not set CPU frequency in boot params - the firmware
does not use frequency passed from the driver, it was only
used by the early pre-production firmware.
With that we can remove CPU frequency calculation code.

Show NPU frequency in FREQ_CHANGE interrupt when frequency
tracking is enabled.

Fixes: 8a27ad81 ("accel/ivpu: Split IP and buttress code")
Cc: stable@vger.kernel.org # v6.11+
Signed-off-by: Andrzej Kacprowski <Andrzej.Kacprowski@intel.com>
Signed-off-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://lore.kernel.org/r/20250401155912.4049340-2-maciej.falkowski@linux.intel.com