content-protection: stop direct accessing core struct member

Commit "weston-log: add function to avoid direct
access to compositor members in non-core code" added the
function weston_compositor_add_log_scope mainly to allow
libweston users to avoid direct accessing core structs, as
weston_compositor.

Replace weston_log_context_add_log_scope usage by
weston_compositor_add_log_scope.

Signed-off-by: Leandro Ribeiro <leandrohr@riseup.net>

libweston/content-protection.c

@@ -340,8 +340,7 @@ weston_compositor_enable_content_protection(struct weston_compositor *compositor
 
 	cp->destroy_listener.notify = cp_destroy_listener;
 	wl_signal_add(&compositor->destroy_signal, &cp->destroy_listener);
-	cp->debug = weston_log_ctx_add_log_scope(compositor->weston_log_ctx,
-				     		 "content-protection-debug",
+	cp->debug = weston_compositor_add_log_scope(compositor, "content-protection-debug",
 						    "debug-logs for content-protection",
 						    NULL, NULL, NULL);
 	return 0;