x86/vsmp: Fix linker error when CONFIG_PROC_FS is not set

set_vsmp_pv_ops() references no_irq_affinity which is undeclared
if CONFIG_PROC_FS isn't set. Fix this by adding an #ifdef around
this variable's access.

Reported-by: Fengguang Wu <[e-mail]>
Signed-off-by: Ido Yariv <[e-mail]>
Acked-by: Shai Fultheim <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/kernel/vsmp_64.c

···
 #ifdef CONFIG_SMP
 	if (cap & ctl & BIT(8)) {
 		ctl &= ~BIT(8);
+#ifdef CONFIG_PROC_FS
+		/* Don't let users change irq affinity via procfs */
 		no_irq_affinity = 1;
+#endif
 	}
 #endif