USB: serial: kl5kusb105: clean up struct definition

Drop redundant packed attribute from the port-settings struct which is
already 1-byte aligned. Also replace __u8 with u8 for the field types as
this is not a structure we share with user space.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>