Kernel: cleanup includes

I went quickly went through all files since I found some weird
includes :D

kernel/include/kernel/Device.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <kernel/FS/FileSystem.h>
 #include <kernel/FS/Inode.h>
 
 namespace Kernel

kernel/include/kernel/Thread.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <BAN/Function.h>
+#include <BAN/Memory.h>
 #include <BAN/NoCopyMove.h>
 
 #include <sys/types.h>