Remove two no-longer-used labels from the NMI interrupt handler.

Reviewed by:	kib

sys/amd64/amd64/exception.S

@@ -663,9 +663,8 @@ outofnmi:
 	cli
 nocallchain:
 #endif
-	testl	%ebx,%ebx
+	testl	%ebx,%ebx	/* %ebx == 0 => return to userland */
 	jnz	doreti_exit
-nmi_kernelexit:
 	/*
 	 * Put back the preserved MSR_GSBASE value.
 	 */
@@ -675,7 +674,6 @@ nmi_kernelexit:
 	shrq	$32,%rdx
 	wrmsr
 	movq	%r13,%cr3
-nmi_restoreregs:
 	RESTORE_REGS
 	addq	$TF_RIP,%rsp
 	jmp	doreti_iret