staging: comedi: das08: rename and rewrite DAS08_INTE

The `DAS08_INTE` macro contains a mask for the "INTE" bit in the control
register (except on "JR" boards).  Setting it to 1 enables interrupts.
Setting it to 0 disables interrupts and clears the "IRQ" bit in the
status register.  Rename the macro to `DAS08_CONTROL_INTE` and add a
comment.  Also use the `BIT()` macro to define its value.  (Note: the
driver does not currently enable interrupts.)

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>