Only set slot to OCCUPIED on successful key loading

Signed-off-by: Ryan Everett <ryan.everett@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 0660ee4..49dd915 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1786,7 +1786,6 @@
      * definition. */
 
     slot->attr = attributes->core;
-    slot->status = PSA_SLOT_OCCUPIED;
     if (PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
 #if !defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
         slot->attr.id = volatile_key_id;
@@ -1850,6 +1849,8 @@
     }
 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
 
+    slot->status = PSA_SLOT_OCCUPIED;
+
     return PSA_SUCCESS;
 }