igt: Remove duplicate igt_display_require() calls

Now that we don't need call igt_display_require() twice, remove the
duplicate calls, previously needed to expose the writeback output.

Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>

benchmarks/kms_fb_stress.c

@@ -150,8 +150,6 @@ igt_simple_main
 
 	data.fd = drm_open_driver_master(DRIVER_ANY);
 
-	igt_display_require(&data.display, data.fd);
-
 	kmstest_set_vt_graphics_mode();
 
 	igt_display_require(&data.display, data.fd);

tests/kms_writeback.c

@@ -563,7 +563,6 @@ igt_main_args("b:c:f:dl", long_options, help_str, opt_handler, NULL)
 
 	igt_fixture {
 		display.drm_fd = drm_open_driver_master(DRIVER_ANY);
-		igt_display_require(&display, display.drm_fd);
 
 		kmstest_set_vt_graphics_mode();