virtio-rng: replace error_set calls with error_setg

Under recommendation from Luiz Capitulino, we are changing
the error_set calls to error_setg while we are fixing up
the error handling pathways of virtio-rng.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index ff58917..03fd04a 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -142,16 +142,15 @@
     Error *local_err = NULL;
 
     if (!vrng->conf.period_ms > 0) {
-        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "period",
-                  "a positive number");
+        error_setg(errp, "'period' parameter expects a positive integer");
         return;
     }
 
     /* Workaround: Property parsing does not enforce unsigned integers,
      * So this is a hack to reject such numbers. */
     if (vrng->conf.max_bytes > INT64_MAX) {
-        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "max-bytes",
-                  "a non-negative integer below 2^63");
+        error_setg(errp, "'max-bytes' parameter must be non-negative, "
+                   "and less than 2^63");
         return;
     }
 
@@ -181,7 +180,7 @@
 
     vrng->rng = vrng->conf.rng;
     if (vrng->rng == NULL) {
-        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object");
+        error_setg(errp, "'rng' parameter expects a valid object");
         return;
     }