Fix status assignments when loading persistent keys

Signed-off-by: Ryan Everett <ryan.everett@arm.com>
diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index 38e3273..5ecc3a7 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -237,12 +237,16 @@
         data = (psa_se_key_data_storage_t *) key_data;
         status = psa_copy_key_material_into_slot(
             slot, data->slot_number, sizeof(data->slot_number));
+
+        if (status == PSA_SUCCESS) {
+            slot->status = PSA_SLOT_OCCUPIED;
+        }
         goto exit;
     }
 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
 
     status = psa_copy_key_material_into_slot(slot, key_data, key_data_length);
-    if (status != PSA_SUCCESS){
+    if (status != PSA_SUCCESS) {
         goto exit;
     }