fix some compile warnings, and fix deprecated qemu option

kernel/Makefile

@@ -91,7 +91,7 @@ ifeq ($(BOARD), qemu)
 qemu_opts += \
 	-drive format=qcow2,file=$(USER_QCOW2),media=disk,cache=writeback,id=sfsimg,if=none \
 	-device ahci,id=ahci0 \
-	-device ide-drive,drive=sfsimg,bus=ahci0.0
+	-device ide-hd,drive=sfsimg,bus=ahci0.0
 endif
 ifeq ($(PCI_PASSTHRU), )
 qemu_net_opts += \

kernel/src/memory.rs

@@ -21,7 +21,6 @@ use bitmap_allocator::BitAlloc;
 use buddy_system_allocator::Heap;
 use core::mem;
 use core::mem::size_of;
-use lazy_static::*;
 use log::*;
 pub use rcore_memory::memory_set::{handler::*, MemoryArea, MemoryAttr};
 use rcore_memory::*;

kernel/src/sync/mutex.rs

@@ -147,14 +147,14 @@ impl<T: ?Sized, S: MutexSupport> Mutex<T, S> {
 
     pub fn ensure_support(&self) {
         let initialization = self.support_initialization.load(Ordering::Relaxed);
-        if (initialization == 2) {
+        if initialization == 2 {
             return;
         };
-        if (initialization == 1
+        if initialization == 1
             || self
                 .support_initialization
                 .compare_and_swap(0, 1, Ordering::Acquire)
-                != 0)
+                != 0
         {
             // Wait for another thread to initialize
             while self.support_initialization.load(Ordering::Acquire) == 1 {