acpid: setrens before ready(), fixing deadlock.

Otherwise, an open call to /scheme/acpi/tables will result in nsmgr
blocking on an `openat(acpi_root, "tables")` call, which will never
occur if acpid is itself blocking on a `ForkNs` call to nsmgr before it
can serve any scheme requests.

drivers/acpid/src/main.rs

@@ -110,11 +110,11 @@ fn daemon(daemon: daemon::Daemon) -> ! {
     register_sync_scheme(&socket, "acpi", &mut scheme)
         .expect("acpid: failed to register acpi scheme to namespace");
 
+    libredox::call::setrens(0, 0).expect("acpid: failed to enter null namespace");
+
     daemon.ready();
     log::info!("acpid ready");
 
-    libredox::call::setrens(0, 0).expect("acpid: failed to enter null namespace");
-
     let mut mounted = true;
     while mounted {
         let Some(event) = event_queue