Use initializers in alloc functions

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 3be67fc..dbcbcc2 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -5582,8 +5582,7 @@
 {
     psa_status_t status;
 
-    local_input->buffer = NULL;
-    local_input->length = 0;
+    *local_input = PSA_CRYPTO_LOCAL_INPUT_INIT;
 
     if (input_len == 0) {
         return PSA_SUCCESS;
@@ -5624,9 +5623,7 @@
 psa_status_t psa_crypto_local_output_alloc(uint8_t *output, size_t output_len,
                                            psa_crypto_local_output_t *local_output)
 {
-    local_output->original = NULL;
-    local_output->buffer = NULL;
-    local_output->length = 0;
+    *local_output = PSA_CRYPTO_LOCAL_OUTPUT_INIT;
 
     if (output_len == 0) {
         return PSA_SUCCESS;