x86/entry/64/compat: Save one instruction in entry_INT80_compat()

As %rdi is never user except in the following push, there is no
need to restore %rdi to the original value.

Signed-off-by: Dominik Brodowski <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Acked-by: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: Dominik Brodowski

arch/x86/entry/entry_64_compat.S

@@ -363,9 +363,7 @@ ENTRY(entry_INT80_compat)
 	pushq	2*8(%rdi)		/* regs->ip */
 	pushq	1*8(%rdi)		/* regs->orig_ax */
 
-	movq	(%rdi), %rdi		/* restore %rdi */
-
-	pushq	%rdi			/* pt_regs->di */
+	pushq	(%rdi)			/* pt_regs->di */
 	pushq	%rsi			/* pt_regs->si */
 	pushq	%rdx			/* pt_regs->dx */
 	pushq	%rcx			/* pt_regs->cx */