[nrf toup] Allow PAKE to use 0 user/peer_id_len

In Matter they use user/peer with id_len set to 0 and this made the
Oberon PSA core to fail because our mbedtls_calloc returns a NULL
pointer.

tracked:
oberon-microsystems/oberon-psa-crypto-nrf#10

Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>

library/psa_crypto.c

@@ -4433,12 +4433,14 @@ psa_status_t psa_pake_set_user(psa_pake_operation_t *operation,
     }
 #endif
 
+	if(user_id_len != 0) {
     operation->inputs.user = mbedtls_calloc(1, user_id_len);
     if (operation->inputs.user == NULL) {
         status = PSA_ERROR_INSUFFICIENT_MEMORY;
         goto exit;
     }
     memcpy(operation->inputs.user, user_id, user_id_len);
+	}
     operation->inputs.user_len = user_id_len;
     operation->user_set = 1;
     return PSA_SUCCESS;
@@ -4483,12 +4485,15 @@ psa_status_t psa_pake_set_peer(psa_pake_operation_t *operation,
     }
 #endif
 
+	if(peer_id_len != 0) {
     operation->inputs.peer = mbedtls_calloc(1, peer_id_len);
     if (operation->inputs.peer == NULL) {
         status = PSA_ERROR_INSUFFICIENT_MEMORY;
         goto exit;
     }
     memcpy(operation->inputs.peer, peer_id, peer_id_len);
+	}
+
     operation->inputs.peer_len = peer_id_len;
     operation->peer_set = 1;
     return PSA_SUCCESS;