staging: comedi: coding style identation error fix

Errors found by checkpatch.pl.
ERROR: code indent should use tabs where possible
/drivers/staging/comedi/drivers/das16m1.c:49
/drivers/staging/comedi/drivers/das16m1.c:50

Signed-off-by: Jaime Arrocha <jarr@kerneldev.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>