Fix two issues in the threshold and completion interrupt mask and unmask
functions. According to the AD714x datasheets the highest stage completion
interrupt should be enabled. Fix mask computation.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Tested-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>