comedi: Fix some signed shift left operations

comedi: Fix some signed shift left operations

Correct some left shifts of the signed integer constant 1 by some
unsigned number less than 32.  Change the constant to 1U to avoid
shifting a 1 into the sign bit.

The corrected functions are comedi_dio_insn_config(),
comedi_dio_update_state(), and __comedi_device_postconfig().

Fixes: e523c6c86232 ("staging: comedi: drivers: introduce comedi_dio_insn_config()")
Fixes: 05e60b13a36b ("staging: comedi: drivers: introduce comedi_dio_update_state()")
Fixes: 09567cb4373e ("staging: comedi: initialize subdevice s->io_bits in postconfig")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250707121555.65424-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>