staging:iio:ad799x fix typo in ad799x_events[]

This patch fixes a typo in ad799x_events[], which caused the error "Failed to register event set".
Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad799x_core.c

@@ -393,7 +393,7 @@ static const struct iio_event_spec ad799x_events[] = {
 	}, {
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_FALLING,
-		.mask_separate = BIT(IIO_EV_INFO_VALUE),
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
 			BIT(IIO_EV_INFO_ENABLE),
 	}, {
 		.type = IIO_EV_TYPE_THRESH,