restapi: Duplicate name 'nics' in schema

QA tools assumes unique element names in the schema (api.xsd),
so naming inner element 'nics', which outer element by this name
already exists in the schema causes failure. Again, the failure
is in the QA tool, and is not a real code or business faliure.
Nevertheless, it's enough of a reason to change the element's name.

Bug-Url: http://bugzilla.redhat.com/1063187
Change-Id: I97a9b1b727053349e3f24c65ffabd69316af1c51
Signed-off-by: Ori Liel <oliel@redhat.com>