Kernel: Use non-locking {Nonnull,}RefPtr for OpenFileDescription

This patch switches away from {Nonnull,}LockRefPtr to the non-locking
smart pointers throughout the kernel.

I've looked at the handful of places where these were being persisted
and I don't see any race situations.

Note that the process file descriptor table (Process::m_fds) was already
guarded via MutexProtected.

Kernel/Devices/Device.cpp

@@ -59,7 +59,7 @@ ErrorOr<NonnullOwnPtr<KString>> Device::pseudo_path(OpenFileDescription const&)
     return KString::formatted("device:{},{}", major(), minor());
 }
 
-ErrorOr<NonnullLockRefPtr<OpenFileDescription>> Device::open(int options)
+ErrorOr<NonnullRefPtr<OpenFileDescription>> Device::open(int options)
 {
     TRY(Process::current().jail().with([&](auto const& my_jail) -> ErrorOr<void> {
         if (my_jail && !is_openable_by_jailed_processes())

Kernel/Devices/Device.h

@@ -43,7 +43,7 @@ public:
     MinorNumber minor() const { return m_minor; }
 
     virtual ErrorOr<NonnullOwnPtr<KString>> pseudo_path(OpenFileDescription const&) const override;
-    virtual ErrorOr<NonnullLockRefPtr<OpenFileDescription>> open(int options) override;
+    virtual ErrorOr<NonnullRefPtr<OpenFileDescription>> open(int options) override;
 
     UserID uid() const { return m_uid; }
     GroupID gid() const { return m_gid; }

Kernel/Devices/KCOVDevice.cpp

@@ -65,7 +65,7 @@ void KCOVDevice::free_process()
     delete kcov_instance;
 }
 
-ErrorOr<NonnullLockRefPtr<OpenFileDescription>> KCOVDevice::open(int options)
+ErrorOr<NonnullRefPtr<OpenFileDescription>> KCOVDevice::open(int options)
 {
     auto pid = Process::current().pid();
     if (proc_instance->get(pid).has_value())

Kernel/Devices/KCOVDevice.h

@@ -23,7 +23,7 @@ public:
 
     // ^File
     ErrorOr<NonnullLockRefPtr<Memory::VMObject>> vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool shared) override;
-    ErrorOr<NonnullLockRefPtr<OpenFileDescription>> open(int options) override;
+    virtual ErrorOr<NonnullRefPtr<OpenFileDescription>> open(int options) override;
 
 protected:
     KCOVDevice();

Kernel/Devices/SelfTTYDevice.cpp

@@ -19,7 +19,7 @@ UNMAP_AFTER_INIT NonnullLockRefPtr<SelfTTYDevice> SelfTTYDevice::must_create()
     return self_tty_device_or_error.release_value();
 }
 
-ErrorOr<NonnullLockRefPtr<OpenFileDescription>> SelfTTYDevice::open(int options)
+ErrorOr<NonnullRefPtr<OpenFileDescription>> SelfTTYDevice::open(int options)
 {
     // Note: If for some odd reason we try to open this device (early on boot?)
     // while there's no current Process assigned, don't fail and return an error.

Kernel/Devices/SelfTTYDevice.h

@@ -24,7 +24,7 @@ private:
     virtual bool is_openable_by_jailed_processes() const override { return true; }
 
     // ^CharacterDevice
-    virtual ErrorOr<NonnullLockRefPtr<OpenFileDescription>> open(int options) override;
+    virtual ErrorOr<NonnullRefPtr<OpenFileDescription>> open(int options) override;
     virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
     virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override;
     virtual bool can_read(OpenFileDescription const&, u64) const override;