Remove amd64_ platform prefix

kernel/amd64/intr.h

@@ -31,7 +31,7 @@ struct saved_regs {
   uint64_t ss;
 } PACKED;
 
-void amd64_load_idt (void);
-void amd64_intr_init (void);
+void idt_load (void);
+void intr_init (void);
 
 #endif // _KERNEL_AMD64_INTR_H