Kernel: Fix interrupt system

I had not understood how MSIs work and I was unnecessarily routing them
through IOAPIC. This is not necessary and should not be done :D

Also MSIs were reserving interrupts that IOAPIC was capable of
generating. Now IOAPIC and MSIs use different set of interrupts so
IOAPIC can use more interrupts if needed.

kernel/include/kernel/Syscall.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <kernel/Attributes.h>
+#include <kernel/IDT.h>
 #include <stdint.h>
 #include <sys/syscall.h>
 
@@ -10,7 +11,16 @@ namespace Kernel
 	ALWAYS_INLINE long syscall(int syscall, uintptr_t arg1 = 0, uintptr_t arg2 = 0, uintptr_t arg3 = 0, uintptr_t arg4 = 0, uintptr_t arg5 = 0)
 	{
 		long ret;
-		asm volatile("int $0x80" : "=a"(ret) : "a"(syscall), "b"((uintptr_t)arg1), "c"((uintptr_t)arg2), "d"((uintptr_t)arg3), "S"((uintptr_t)arg4), "D"((uintptr_t)arg5) : "memory");
+		asm volatile("int %[irq]"
+			: "=a"(ret)
+			: [irq]"i"(IRQ_SYSCALL)
+			, "a"(syscall)
+			, "b"((uintptr_t)arg1)
+			, "c"((uintptr_t)arg2)
+			, "d"((uintptr_t)arg3)
+			, "S"((uintptr_t)arg4)
+			, "D"((uintptr_t)arg5)
+			: "memory");
 		return ret;
 	}