x86/resume: take care of fully eager FPU around system suspend

Just like in the HVM emulation and EFI runtime call cases we must not
set CR0.TS here in fully eager mode. Note that idle vCPU-s never have
->arch.fully_eager_fpu set (for their initialization not going through
vcpu_init_fpu()), so we won't hit the respective ASSERT() in
vcpu_restore_fpu_eager(). 

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
RFC: Not even compile tested, as I'm writing this from home.

--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -92,8 +92,11 @@ void restore_rest_processor_state(void)
         write_debugreg(7, curr->arch.debugreg[7]);
     }
 
-    /* Reload FPU state on next FPU use. */
-    stts();
+    /* Reload FPU state immediately or on next FPU use. */
+    if ( curr->arch.fully_eager_fpu )
+        vcpu_restore_fpu_eager(curr);
+    else
+        stts();
 
     if (cpu_has_pat)
         wrmsrl(MSR_IA32_CR_PAT, host_pat);