Move Io/Pio/Mmio from redox_syscall to common

* Fix Mmio repr from transparent to packed.
* Rename Mmio::from to Mmio::new.
* Remove dead imports around affected code.
* Minor formatting.

acpid/src/acpi.rs

@@ -6,7 +6,7 @@ use std::sync::{Arc, Mutex};
 use std::{fmt, mem};
 
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-use syscall::io::{Io, Pio};
+use common::io::{Io, Pio};
 
 use parking_lot::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 use thiserror::Error;

acpid/src/acpi/dmar/drhd.rs

@@ -1,6 +1,6 @@
 use std::ops::{Deref, DerefMut};
 
-use syscall::io::Mmio;
+use common::io::Mmio;
 
 // TODO: Only wrap with Mmio where there are hardware-registers. (Some of these structs seem to be
 // ring buffer entries, which are not to be treated the same way).

acpid/src/acpi/dmar/mod.rs

@@ -10,7 +10,7 @@ use std::convert::TryFrom;
 use std::ops::Deref;
 use std::{fmt, mem};
 
-use syscall::io::Io as _;
+use common::io::Io as _;
 
 use num_derive::FromPrimitive;
 use num_traits::FromPrimitive;

acpid/src/aml_physmem.rs

@@ -3,7 +3,8 @@ use rustc_hash::FxHashMap;
 use std::fmt::LowerHex;
 use std::mem::size_of;
 use std::sync::{Arc, Mutex};
-use syscall::{Io, Pio, PAGE_SIZE};
+use syscall::PAGE_SIZE;
+use common::io::{Io, Pio};
 
 const PAGE_MASK: usize = !(PAGE_SIZE - 1);
 const OFFSET_MASK: usize = PAGE_SIZE - 1;