Fix typo in platform macro defines for examples
diff --git a/programs/pkey/dh_client.c b/programs/pkey/dh_client.c
index 68f0df5..7ec47ac 100644
--- a/programs/pkey/dh_client.c
+++ b/programs/pkey/dh_client.c
@@ -32,7 +32,7 @@
 #include <stdlib.h>
 #define mbedtls_printf          printf
 #define mbedtls_time_t          time_t
-#define MBEDTLS_EXTI_SUCCESS    EXIT_SUCCESS
+#define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
 #endif /* MBEDTLS_PLATFORM_C */