system/dirtylimit: Drop the reduplicative check

Checking if dirty limit is in service is done by the
dirtylimit_query_all function, drop the reduplicative
check in the qmp_query_vcpu_dirty_limit function.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <df9c3514933ff6750ef88068af18d3054bedf746.1698847223.git.yong.huang@smartx.com>

system/dirtylimit.c

@@ -652,10 +652,6 @@ static struct DirtyLimitInfoList *dirtylimit_query_all(void)
 
 struct DirtyLimitInfoList *qmp_query_vcpu_dirty_limit(Error **errp)
 {
-    if (!dirtylimit_in_service()) {
-        return NULL;
-    }
-
     return dirtylimit_query_all();
 }