aio / timers: Rename qemu_timer_* functions

Rename four functions in preparation for new API.

Rename qemu_timer_expired to timer_expired
Rename qemu_timer_expire_time_ns to timer_expire_time_ns
Rename qemu_timer_pending to timer_pending
Rename qemu_timer_expired_ns to timer_expired_ns

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/savevm.c b/savevm.c
index 03fc4d9..38c3093 100644
--- a/savevm.c
+++ b/savevm.c
@@ -983,7 +983,7 @@
 {
     uint64_t expire_time;
 
-    expire_time = qemu_timer_expire_time_ns(ts);
+    expire_time = timer_expire_time_ns(ts);
     qemu_put_be64(f, expire_time);
 }