target/i386: SEV: fix mismatch in vcek-disabled property name

The vcek-disabled property of the sev-snp-guest object is misspelled
vcek-required (which I suppose would use the opposite polarity) in
the call to object_class_property_add_bool().  Fix it.

Reported-by: Zixi Chen <zixchen@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/target/i386/sev.c b/target/i386/sev.c
index a1157c0..a0d271f 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -2422,7 +2422,7 @@
     object_class_property_add_bool(oc, "author-key-enabled",
                                    sev_snp_guest_get_author_key_enabled,
                                    sev_snp_guest_set_author_key_enabled);
-    object_class_property_add_bool(oc, "vcek-required",
+    object_class_property_add_bool(oc, "vcek-disabled",
                                    sev_snp_guest_get_vcek_disabled,
                                    sev_snp_guest_set_vcek_disabled);
     object_class_property_add_str(oc, "host-data",