x86/idt: Remove unused macro SISTG

Commit

  d8ba61ba ("x86/entry/64: Don't use IST entry for #BP stack")

removed the last user but left the macro around.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160144.050689789@linutronix.de

arch/x86/kernel/idt.c

@@ -45,10 +45,6 @@ struct idt_data {
 #define ISTG(_vector, _addr, _ist)			\
 	G(_vector, _addr, _ist, GATE_INTERRUPT, DPL0, __KERNEL_CS)
 
-/* System interrupt gate with interrupt stack */
-#define SISTG(_vector, _addr, _ist)			\
-	G(_vector, _addr, _ist, GATE_INTERRUPT, DPL3, __KERNEL_CS)
-
 /* Task gate */
 #define TSKG(_vector, _gdt)				\
 	G(_vector, NULL, DEFAULT_STACK, GATE_TASK, DPL0, _gdt << 3)