tidy up syntax

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 2a75983..f0da0dd 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4464,11 +4464,9 @@
 
 #if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
     if (ssl->conf != NULL) {
-        if (ssl->conf->f_async_cancel != NULL) {
-            if (handshake->async_in_progress != 0) {
+        if (ssl->conf->f_async_cancel != NULL && handshake->async_in_progress != 0) {
                 ssl->conf->f_async_cancel(ssl);
                 handshake->async_in_progress = 0;
-            }
         }
     }