Kernel: Rewrite whole device structure

We now have DevFileSystem which is derived from RamFileSystem. All
devices are RamInodes. We don't have separate DeviceManager anymore.
To iterate over devices, you can loop througn every inode in devfs.

kernel/kernel/kernel.cpp

@@ -1,7 +1,7 @@
 #include <kernel/ACPI.h>
 #include <kernel/Arch.h>
 #include <kernel/Debug.h>
-#include <kernel/DeviceManager.h>
+#include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/FS/VirtualFileSystem.h>
 #include <kernel/GDT.h>
 #include <kernel/IDT.h>
@@ -140,6 +140,9 @@ extern "C" void kernel_main()
 	ASSERT(terminal_driver);
 	dprintln("VESA initialized");
 
+	DevFileSystem::initialize();
+	dprintln("devfs initialized");
+
 	TTY* tty1 = new TTY(terminal_driver);
 	ASSERT(tty1);
 	dprintln("TTY initialized");
@@ -147,9 +150,6 @@ extern "C" void kernel_main()
 	parse_command_line();
 	dprintln("command line parsed, root='{}'", cmdline.root);
 
-	PCI::initialize();
-	dprintln("PCI initialized");
-
 	MUST(ACPI::initialize());
 	dprintln("ACPI initialized");
 
@@ -160,6 +160,8 @@ extern "C" void kernel_main()
 	dprintln("PIT initialized");
 
 	MUST(Scheduler::initialize());
+	dprintln("Scheduler initialized");
+
 	Scheduler& scheduler = Scheduler::get();
 	Process::create_kernel(init2, tty1);
 	scheduler.start();
@@ -172,9 +174,13 @@ static void init2(void* tty1)
 	using namespace Kernel;
 	using namespace Kernel::Input;
 
-	DeviceManager::get().initialize_pci_devices();
-	DeviceManager::get().initialize_updater();
+	dprintln("Scheduler started");
 
+	DevFileSystem::get().initialize_device_updater();
+
+	PCI::initialize();
+	dprintln("PCI initialized");
+	
 	VirtualFileSystem::initialize(cmdline.root);
 
 	if (auto res = PS2Controller::initialize(); res.is_error())