Drivers: hv: vmbus: Don't leak channel ids

If we cannot allocate memory for the channel, free the relid
associated with the channel.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>