x86/pvh: add prototype for xen_pvh_init()

xen_pvh_init() is lacking a prototype in a header, add it.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20211006061950.9227-1-jgross@suse.comReviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

arch/x86/include/asm/xen/hypervisor.h

@@ -62,4 +62,8 @@ void xen_arch_register_cpu(int num);
 void xen_arch_unregister_cpu(int num);
 #endif
 
+#ifdef CONFIG_PVH
+void __init xen_pvh_init(struct boot_params *boot_params);
+#endif
+
 #endif /* _ASM_X86_XEN_HYPERVISOR_H */