WorkQueue: Fix up arch-specific work items where possible

Fix up arch-specific work items where possible to use the new work_struct and
delayed_work structs.

Three places that enqueue bits of their stack and then return have been marked
with #error as this is not permitted.

Signed-Off-By: David Howells <dhowells@redhat.com>
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 7b17216..96f0189 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -56,7 +56,7 @@
 
 static LIST_HEAD(mc_requests);
 
-static void mc_work_proc(void *unused)
+static void mc_work_proc(struct work_struct *unused)
 {
 	struct mconsole_entry *req;
 	unsigned long flags;
@@ -72,7 +72,7 @@
 	}
 }
 
-static DECLARE_WORK(mconsole_work, mc_work_proc, NULL);
+static DECLARE_WORK(mconsole_work, mc_work_proc);
 
 static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
 {