qemu: monitor cleanup delvm error handling

Drop redundant NULL checks, and add an error string prefix
Acked-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

src/qemu/qemu_monitor_text.c

@@ -259,16 +259,17 @@ int qemuMonitorTextDeleteSnapshot(qemuMonitorPtr mon, const char *name)
     if (qemuMonitorHMPCommand(mon, cmd, &reply))
         goto cleanup;
 
-    if (strstr(reply, "No block device supports snapshots") != NULL) {
+    if (strstr(reply, "No block device supports snapshots")) {
         virReportError(VIR_ERR_OPERATION_INVALID, "%s",
                        _("this domain does not have a device to delete snapshots"));
         goto cleanup;
-    } else if (strstr(reply, "Snapshots not supported on device") != NULL) {
+    } else if (strstr(reply, "Snapshots not supported on device")) {
         virReportError(VIR_ERR_OPERATION_INVALID, "%s", reply);
         goto cleanup;
-    } else if (strstr(reply, "Error") != NULL
-             && strstr(reply, "while deleting snapshot") != NULL) {
-        virReportError(VIR_ERR_OPERATION_FAILED, "%s", reply);
+    } else if (strstr(reply, "Error") &&
+               strstr(reply, "while deleting snapshot")) {
+        virReportError(VIR_ERR_OPERATION_FAILED,
+                       _("Failed to delete snapshot: %s"), reply);
         goto cleanup;
     }