Staging: comedi: kcomedilib: Fixed a typo

Fixed a typo in kcomedilib_main.c file.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/kcomedilib/kcomedilib_main.c

@@ -95,7 +95,7 @@ static int comedi_do_insn(struct comedi_device *dev,
 
 	if (s->type == COMEDI_SUBD_UNUSED) {
 		dev_err(dev->class_dev,
-			"%d not useable subdevice\n", insn->subdev);
+			"%d not usable subdevice\n", insn->subdev);
 		ret = -EIO;
 		goto error;
 	}