x86: cpu: bugs.c: Fix compile error when CONFIG_XEN=n

Fix compile error in bugs.c when CONFIG_XEN=n.

Orabug: 30516915

Signed-off-by: Aaron Young <aaron.young@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>

Author: ajyoung-oracle

arch/x86/kernel/cpu/bugs.c

@@ -16,6 +16,7 @@
 #include <linux/prctl.h>
 #include <linux/jump_label.h>
 #include <linux/sched/smt.h>
+#include <xen/xen.h>
 
 #include <asm/spec-ctrl.h>
 #include <asm/cmdline.h>