Fixes syntax and naming for check-names.sh

Some macros were failing checks by check-names.sh
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 69a6afd..039cb58 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -234,11 +234,11 @@
 /*
  * The time_t datatype
  */
-#if defined(MBEDTLS_PLATFORM_TIME_T_MACRO)
-#define mbedtls_time_t MBEDTLS_PLATFORM_TIME_T_MACRO
+#if defined(MBEDTLS_PLATFORM_TIME_TYPE_MACRO)
+typedef MBEDTLS_PLATFORM_TIME_TYPE_MACRO mbedtls_time_t;
 #else
-#define mbedtls_time_t time_t
-#endif /* MBEDTLS_PLATFORM_TIME_T_MACRO */
+typedef time_t mbedtls_time_t;
+#endif /* MBEDTLS_PLATFORM_TIME_TYPE_MACRO */
 
 /*
  * The function pointers for time