peer: unconditionally add a channel to the switch if it's open
peer: unconditionally add a channel to the switch if it's open

In this commit we revert a prior change which was added after
FundingLocked retransmission was implemented. This prior change didn’t
factor in the fact that the FundingLocked message will *only* be
re-sent after both sides receive the ChannelReestablishment message.
With the prior code, as we never added the channel to the link, we’d
never re-send the ChannelReestablishment, meaning the other side would
never send the FundingLocked message.

By unconditionally adding the channel to the switch, we ensure that
we’ll always properly retransmit the FundingLocked message.

LightningNetwork/lnd,LightningNetwork/lnd,aakselrod/lnd,aakselrod/lnd