staging/fwserial: Only reset port status for attached peers

When a port has been reserved in an attempt to connect to a peer
but that attempt does not succeed, releasing the port should not
reset the port line status. Although resetting is functionally
harmless, it can appear as if a remote peer dropped carrier to a
port it was not attached to (which can be confusing).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>