[nrf fromtree] ITS: Fix return code

Fix incorrect error code to align with what TFM_S_ITS_TEST_1020 expects.

Change-Id: I1a5ac1440a4784953f0ae28220dd79b2cf1fc596
Signed-off-by: Vidar Lillebø <[email protected]>
(cherry picked from commit 26d594c472b58bf1391b910d86c1457e7e64bb49)

secure_fw/partitions/internal_trusted_storage/tfm_internal_trusted_storage.c

@@ -103,7 +103,7 @@ static psa_status_t buffer_size_check(int32_t client_id, size_t buffer_size)
          * global buffer.
          */
         if (buffer_size > sizeof(enc_asset_data)) {
-            return PSA_ERROR_BUFFER_TOO_SMALL;
+            return PSA_ERROR_INVALID_ARGUMENT;
         }
     }
     return PSA_SUCCESS;