Change the rng-function name

Change the name to mbedtls_platform_random_in_range
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index b3d0c91..92283ad 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -170,7 +170,7 @@
 
 int mbedtls_platform_memcmp( const void *buf1, const void *buf2, size_t num );
 
-size_t mbedtls_random_in_range( size_t num );
+size_t mbedtls_platform_random_in_range( size_t num );
 
 #if defined(MBEDTLS_HAVE_TIME_DATE)
 /**