Update library/timing.c

Co-authored-by: Gilles Peskine <gilles.peskine@arm.com>
Signed-off-by: Gianfranco Costamagna <costamagnagianfranco@yahoo.it>
diff --git a/library/timing.c b/library/timing.c
index 2777f6f..b1f72fe 100644
--- a/library/timing.c
+++ b/library/timing.c
@@ -401,7 +401,7 @@
     uint32_t a = 0, b = 0;
     mbedtls_timing_delay_context ctx;
 
-    memset(ctx, 0, sizeof(ctx));
+    memset(&ctx, 0, sizeof(ctx));
     if (verbose != 0) {
         mbedtls_printf("  TIMING tests note: will take some time!\n");
     }