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/suites/main_test.function b/tests/suites/main_test.function
index ff4cf20..af4b84e 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -261,7 +261,7 @@
  */
 int main( int argc, const char *argv[] )
 {
-    int ret = platform_setup();
+    int ret = mbedtls_test_platform_setup();
     if( ret != 0 )
     {
         mbedtls_fprintf( stderr,
@@ -271,6 +271,6 @@
     }
 
     ret = execute_tests( argc, argv );
-    platform_teardown();
+    mbedtls_test_platform_teardown();
     return( ret );
 }