[PATCH] xen: Fix build with recent suspend_hvm.c changes

[Vitaly Kuznetsov]

kbuild test robot reports the following issues with some randconfig build:
...
In file included from ./include/xen/interface/hvm/params.h:24,
                 from ./include/xen/hvm.h:6,
                 from arch/x86/xen/suspend_hvm.c:5:
./include/xen/interface/hvm/hvm_op.h:29:5: error: unknown type name âdomid_tâ
   29 |     domid_t  domid;    /* IN */
      |     ^~~~~~~
./include/xen/interface/hvm/hvm_op.h:33:1: warning: data definition has no
  type or storage class
   33 | DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_param);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
./include/xen/interface/hvm/hvm_op.h:33:1: error: type defaults to âintâ in
  declaration of âDEFINE_GUEST_HANDLE_STRUCTâ [-Werror=implicit-int]
...

These definitions are in xen/interface/xen.h, add the include to hvm.h.

Fixes: 28447ea41542 ("xen: Move xen_setup_callback_vector() definition to include/xen/hvm.h")
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
- I'm failing to see why this was compiling when 28447ea41542 ("xen: Move
 xen_setup_callback_vector() definition to include/xen/hvm.h") was
 submitted, just keeping playing whack-a-mole game fixing the immediate
 issue, thanks kbuild robot for the report!
---
 include/xen/hvm.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/xen/hvm.h b/include/xen/hvm.h
index b7fd7fc9ad41..7cf0c529ab4a 100644
--- a/include/xen/hvm.h
+++ b/include/xen/hvm.h
@@ -3,6 +3,7 @@
 #ifndef XEN_HVM_H__
 #define XEN_HVM_H__
 
+#include <xen/interface/xen.h>
 #include <xen/interface/hvm/params.h>
 #include <asm/xen/hypercall.h>
 
-- 
2.25.4