Revert "Merge pull request #11 from sushilrai/untag_vlan_hang"

This reverts commit 5eaa65fe7bac2c62a3fa5608715a466cd2428be1, reversing
changes made to 74c64eed01280d77a048f73f1c958b4d54363851.

This commit caused vlans to fail to get configured on mxls. Need to
revisit the original purpose of this commit, which was to improve
error handling if the untag configuration failed.