accel/ivpu: Correct DCT interrupt handling

Fix improper use of dct_active_percent field in DCT interrupt handler
causing DCT to never get enabled. Set dct_active_percent internally before
IPC to ensure correct driver value even if IPC fails.
Set default DCT value to 30 accordingly to HW architecture specification.

Fixes: a19bffb1 ("accel/ivpu: Implement DCT handling")
Signed-off-by: Karol Wachowski <karol.wachowski@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/20250416102616.384577-1-maciej.falkowski@linux.intel.com