Free incompletely initialized dvcs.

If dynamic channels are not completely initialized, the server will
reuse those channel numbers for new channels.
This causes interesting problems when the server asks for a channel
by number, as we can end up with multiple channels with the same number.

Log example of the problem:
DBG_DVC drdynvc_process_receive (341): Cmd=0x1
DBG_DVC drdynvc_process_create_request (249): ChannelId=0 ChannelName=PNPDR
DBG_DVC drdynvc_process_create_request (265): no listener
DBG_DVC drdynvc_process_receive (341): Cmd=0x1
DBG_DVC drdynvc_process_create_request (249): ChannelId=0 ChannelName=TSMF
DBG_DVC tsmf_on_new_channel_connection (378):
DBG_DVC dvcman_create_channel (415): listener TSMF created new channel 0
DBG_DVC drdynvc_process_create_request (260): channel created
DBG_DVC drdynvc_process_receive (341): Cmd=0x3
DBG_DVC drdynvc_process_data (311): ChannelId=0
Warning dvcman_receive_channel_data (517): ChannelId 0 not ready!

In this log, we received data intended for TSMF, but the channel lookup
found the incompletely initialized PNPDR.
Merge pull request #1288 from dbungert/dvcmanDupeChannels

Free incompletely initialized dvcs.