Changes

tcap_as_loadshare_vty: Avoid possible NULL pointer dereference

argv[1]/as_name is always set so the `if (as_name)` guard can be
removed. This lets Coverity verify that as is never dereferenced if
NULL.

Related: Coverity CID#551555
Change-Id: Ia9151ae63be3977c2eccf246316b99c20284dbe2