lisp: API doc/comments cleanup

lisp: API doc/comments cleanup

Removing the comments around eid_type which seem to have been overlooked
by the original patch https://gerrit.fd.io/r/c/vpp/+/24663.

NOTE: This patch is a doc-only change. It does two things:
    1. Remove comments around obsolete eid_type type
    2. Update the comments to reflect the new vl_api_eid_t type

This is to ensure correct documentation is displayed to user/reader of
VPP docs in 20.05.

Type: fix

Signed-off-by: Onong Tayeng <otayeng@cisco.com>
Change-Id: I48e1993cf8869cb32e159d1956f3ec1e5943e33f
(cherry picked from commit 4ab5190eb4167ac4c06cd649ec8a860784ab1d41)