Remove intr function not in line with int 21h

If we have them, use them for setting up ourselves

kernel/main.asm

@@ -7,10 +7,12 @@ isr_dos_main:
   je isr_getc_echo
   cmp ah, 0x02
   je isr_putc
+  cmp ah, 0x25
+  je isr_intr_register
   jmp isr_invalid
 
-%include "chario.asm"
 %include "intr.asm"
+%include "chario.asm"
 
 %include "cache.asm"
 
@@ -32,14 +34,15 @@ isr_return:
   iret
 
 init:
-  push cs
-  pop es
-  mov di, isr_dos_main
-  mov ax, 0x21
-  call intr_register
+  mov ax, cs
+  mov ds, ax
+  mov es, ax
 
-  mov di, kernel_end
-  call cache_init
+  mov dx, isr_dos_main
+  mov ax, 0x2521
+  pushf
+  push cs
+  call isr_dos_main
 
   int3