Replace zero by PSA_ALG_NONE in key derivation internal functions

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 55eadc4..b01f948 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -4751,7 +4751,7 @@
     psa_status_t status;
     psa_algorithm_t kdf_alg = psa_key_derivation_get_kdf_alg(operation);
 
-    if (kdf_alg == 0) {
+    if (kdf_alg == PSA_ALG_NONE) {
         /* This is a blank or aborted operation. */
         status = PSA_ERROR_BAD_STATE;
         goto exit;