net: Do not include a newline in the id of -nic devices

net: Do not include a newline in the id of -nic devices

The '\n' sneaked in by accident here, an "id" string should really
not contain a newline character at the end.

Fixes: 78cd6f7bf6b ('net: Add a new convenience option "--nic" ...')
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200518074352.23125-1-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
(cherry picked from commit 0561dfac082becdd9e89110249a27b309b62aa9f)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>