nrf_security: CRACEN: Update KMU provisioning slot

Change KMU provisioning slot from 250 to 186
Slot 250 is supposed to be reserved for other usage
Slot 186 is directly after an already reserved slot

Signed-off-by: Dag Erik Gjørvad <[email protected]>

Author: degjorva

doc/nrf/app_dev/device_guides/nrf54l/cryptography.rst

@@ -78,7 +78,11 @@ The following table gives an overview of the KMU slots and their usage:
    * - 183-185
      - IKG seed
      - 384-bit random seed to generate keys using the CRACEN IKG.
-   * - 186-225
+   * - 186
+     - Provisioning slot
+     - | Reserved slot for internal KMU usage.
+       | This slot is used to validate that provisioning of the KMU slots is completed.
+   * - 187-225
      - Reserved
      - --
    * - 226-227

subsys/nrf_security/src/drivers/cracen/cracenpsa/src/kmu.c

@@ -25,7 +25,7 @@
  *      Bits 15-8:  slot-id
  *      Bits 7-0:   number of slots
  */
-#define PROVISIONING_SLOT 250
+#define PROVISIONING_SLOT 186
 
 #define SECONDARY_SLOT_METADATA_VALUE UINT32_MAX