Re-add XHCI DbC console fixes

Re-add patches fixing XHCI DbC console when sys-usb is running, as they
haven't made it to Xen 4.19.
See 1d786af for more context.

0300-xen-list-add-LIST_HEAD_RO_AFTER_INIT.patch

@@ -0,0 +1,34 @@
+From 2e1e0504cc52901689d15517459163b4159c8110 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
+ <[email protected]>
+Date: Tue, 23 Jul 2024 13:59:12 +0200
+Subject: [PATCH] xen/list: add LIST_HEAD_RO_AFTER_INIT
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Similar to LIST_HEAD_READ_MOSTLY.
+
+Signed-off-by: Marek Marczykowski-Górecki <[email protected]>
+Acked-by: Jan Beulich <[email protected]>
+---
+ xen/include/xen/list.h | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/xen/include/xen/list.h b/xen/include/xen/list.h
+index 6506ac40893b..62169f46742e 100644
+--- a/xen/include/xen/list.h
++++ b/xen/include/xen/list.h
+@@ -42,6 +42,9 @@ struct list_head {
+ #define LIST_HEAD_READ_MOSTLY(name) \
+     struct list_head __read_mostly name = LIST_HEAD_INIT(name)
+
++#define LIST_HEAD_RO_AFTER_INIT(name) \
++    struct list_head __ro_after_init name = LIST_HEAD_INIT(name)
++
+ static inline void INIT_LIST_HEAD(struct list_head *list)
+ {
+     list->next = list;
+-- 
+2.46.0
+