lib/igt_kms: set_vt_graphics_mode is a low-level helper

So give it a kmstest_ prefix and shuffle it around a bit.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/tests/kms_flip_tiling.c b/tests/kms_flip_tiling.c
index ca20ad9..6f8ee94 100644
--- a/tests/kms_flip_tiling.c
+++ b/tests/kms_flip_tiling.c
@@ -128,7 +128,7 @@
 	igt_fixture {
 		data.drm_fd = drm_open_any();
 
-		igt_set_vt_graphics_mode();
+		kmstest_set_vt_graphics_mode();
 
 		igt_require_pipe_crc();
 		igt_display_init(&data.display, data.drm_fd);