IF update - 14: updating logical interface stacking handler

Updated the #logical-interface #stack #handling routines in IF module. The #stacking #change #handler routines has been #upgraded for the new data-structure changes. The interface stacking change handler will #check with the #upper and #lower #interface #layer s #on #create / #remove operations for each stack slice. e.g. On adding a #TE-Link over an #ethernet port the port capability (L2/L3/MPLS, bandwidth, MTU, duplexity, etc ...) and it's current state (OPER-STATUS) is checked. On creating the TE-Link TE-Link bandwidth is deduced from the lower layer ethernet port speed/bandwidth. On removing an GMPLS / #MPLS-tunnel, the earlier reserved bandwidth is returned back to it's lower layer #MPLS-interface and #TE-Link. These operations are supported through the interface stack change handler.

#IF update 14 ...
[commit 57a5237d1912bcff8c85f1e3d4448c52311a44f1] (https://github.com/nes-repo/NES-Open-Switch/commit/57a5237d1912bcff8c85f1e3d4448c52311a44f1)