x86: drop an effectively unused struct pv_vcpu field

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Split original patch into two.

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -901,7 +901,6 @@ int arch_set_info_guest(
         v->arch.pv_vcpu.event_callback_cs = c(event_callback_cs);
         v->arch.pv_vcpu.failsafe_callback_cs = c(failsafe_callback_cs);
     }
-    v->arch.pv_vcpu.vm_assist = c(vm_assist);
 
     /* Only CR0.TS is modifiable by guest or admin. */
     v->arch.pv_vcpu.ctrlreg[0] &= X86_CR0_TS;
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1436,7 +1436,6 @@ void arch_get_info_guest(struct vcpu *v,
             c(event_callback_cs = v->arch.pv_vcpu.event_callback_cs);
             c(failsafe_callback_cs = v->arch.pv_vcpu.failsafe_callback_cs);
         }
-        c(vm_assist = v->arch.pv_vcpu.vm_assist);
 
         /* IOPL privileges are virtualised: merge back into returned eflags. */
         BUG_ON((c(user_regs.eflags) & X86_EFLAGS_IOPL) != 0);
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -372,8 +372,6 @@ struct pv_vcpu
         };
     };
 
-    unsigned long vm_assist;
-
     unsigned long syscall32_callback_eip;
     unsigned long sysenter_callback_eip;
     unsigned short syscall32_callback_cs;