hso: Use static attribute groups for sysfs entry

Pass the static attribute groups and the driver data via
tty_port_register_device_attr() instead of manual device_create_file()
and device_remove_file() calls.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>