CRM-13591 : fixed condition check for display value returning function for custom fields (i.e used for returning appropriate val for Yes/No fields)

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* CRM-13591: Yes / No fields are not properly displayed in profile view
  http://issues.civicrm.org/jira/browse/CRM-13591
Merge pull request #1796 from pratik-joshi/CRM-13591

CRM-13591 : fixed condition check for display value returning function for custom fields (i.e used for returning appropriate val for Yes/No fields)