Switch PSA_HASH_FINAL_SIZE to PSA_HASH_SIZE

Make this macro work on derived algorithms as well (HMAC,
hash-and-sign, etc.).
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 3ea87f6..b66862c 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -774,7 +774,7 @@
                               size_t *hash_length )
 {
     int ret;
-    size_t actual_hash_length = PSA_HASH_FINAL_SIZE( operation->alg );
+    size_t actual_hash_length = PSA_HASH_SIZE( operation->alg );
 
     /* Fill the output buffer with something that isn't a valid hash
      * (barring an attack on the hash and deliberately-crafted input),