tests: Add mbedtls_test_ prefix to platform_* functions

Add mbedtls_test_ prefix to platform_setup() and
platform_teardown() test helper functions.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index 9194ada..817353a 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -50,8 +50,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
-int platform_setup( void );
-void platform_teardown( void );
+int mbedtls_test_platform_setup( void );
+void mbedtls_test_platform_teardown( void );
 
 int unhexify( unsigned char *obuf, const char *ibuf );
 void hexify( unsigned char *obuf, const unsigned char *ibuf, int len );