Revert "Refactor `psa_load_persistent_key_into_slot` to remove bad `goto`"

This reverts commit d69f4017fbf949ab3aceca178b034b73e6e43dbc.

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 0278009..5ecc3a7 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -234,10 +234,14 @@
             status = PSA_ERROR_DATA_INVALID;
             goto exit;
         }
-
         data = (psa_se_key_data_storage_t *) key_data;
-        key_data = data->slot_number;
-        key_data_length = sizeof(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 */