Temporarily reverted "Update ietf-inet-types and ietf-yang-types with RFC6991"

Upstream dependencies did not honor warnings which required them to specify model revision.

Change-Id: I7ac5d5820bf47fb2e429eb8b8c6ef060b6eab652
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Merge "Temporarily reverted "Update ietf-inet-types and ietf-yang-types with RFC6991""