target-i386: Disable CPUID_ACPI by default in KVM mode

KVM never supported the CPUID_ACPI flag, so it doesn't make sense to
have it enabled by default when KVM is enabled.

The motivation here is exactly the same we had for the MONITOR flag
(disabled by commit 136a7e9).

And like in the MONITOR flag case, we don't need machine-type compat code
because it is currently impossible to run a KVM VM with the ACPI flag set.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

target-i386/cpu.c

@@ -459,6 +459,7 @@ static uint32_t kvm_default_features[FEATURE_WORDS] = {
 /* Features that are not added by default to any CPU model when KVM is enabled.
  */
 static uint32_t kvm_default_unset_features[FEATURE_WORDS] = {
+    [FEAT_1_EDX] = CPUID_ACPI,
     [FEAT_1_ECX] = CPUID_EXT_MONITOR,
 };