conf: Remove obsolete comment

The virDomainDeviceInfoIsSet() function no longer exists.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NLaine Stump <laine@laine.org>

src/conf/device_conf.h

@@ -134,10 +134,6 @@ struct _virDomainDeviceDimmAddress {
 typedef struct _virDomainDeviceInfo virDomainDeviceInfo;
 typedef virDomainDeviceInfo *virDomainDeviceInfoPtr;
 struct _virDomainDeviceInfo {
-    /* If adding to this struct, ensure that
-     * virDomainDeviceInfoIsSet() is updated
-     * to consider the new fields
-     */
     char *alias;
     int type; /* virDomainDeviceAddressType */
     union {