backend-drm: Fix ignoring config 'require-input' option

Without this patch, the DRM-backend would rewrite the 'require-input',
core section option given by the user.

This removes 'continue_without_input' DRM-backend option and takes into
consideration the cmd line option only if that was passed (Pekka Paalanen).

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

libweston/backend-drm/drm.c

@@ -3025,7 +3025,6 @@ drm_backend_create(struct weston_compositor *compositor,
 						   NULL, NULL, NULL);
 
 	compositor->backend = &b->base;
-	compositor->require_input = !config->continue_without_input;
 
 	if (parse_gbm_format(config->gbm_format, DRM_FORMAT_XRGB8888, &b->gbm_format) < 0)
 		goto err_compositor;