xhci: dbctty: disable ECHO flag by default

xhci: dbctty: disable ECHO flag by default

When /dev/ttyDBC0 device is created then by default ECHO flag
is set for the terminal device. However if data arrives from
a peer before application using /dev/ttyDBC0 applies its set
of terminal flags then the arriving data will be echoed which
might not be desired behavior.

Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.")
Cc: stable <stable@kernel.org>
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/stable/20250610111802.18742-1-ukaszb%40chromium.org
Link: https://lore.kernel.org/r/20250627144127.3889714-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>