x86/asm/entry/64: Remove pointless jump to irq_return

INTERRUPT_RETURN turns into a jmp instruction.  There's no need
for extra indirection.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2f2318653dbad284a59311f13f08cea71298fd7c.1433449436.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/entry_64.S

@@ -663,8 +663,6 @@ retint_kernel:
 restore_c_regs_and_iret:
 	RESTORE_C_REGS
 	REMOVE_PT_GPREGS_FROM_STACK 8
-
-irq_return:
 	INTERRUPT_RETURN
 
 ENTRY(native_iret)
@@ -1432,7 +1430,7 @@ nmi_restore:
 
 	/* Clear the NMI executing stack variable */
 	movq $0, 5*8(%rsp)
-	jmp irq_return
+	INTERRUPT_RETURN
 END(nmi)
 
 ENTRY(ignore_sysret)