kni: query the name of an instance

kni: query the name of an instance

When a KNI object is created, a name is assigned to it which is stored
internally. There is also an API function to look up a KNI object by
name, but there is no API to query the current name of an existing
KNI object. This patch adds just such an API.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>