MAINTAINERS: add missing files to the adis lib

The triggered buffer support was missing in the MAINTAINERS file. Add
them.
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220122130905.99-1-nuno.sa@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -1120,6 +1120,8 @@ M:	Nuno Sa <nuno.sa@analog.com>
 L:	linux-iio@vger.kernel.org
 S:	Supported
 F:	drivers/iio/imu/adis.c
+F:	drivers/iio/imu/adis_buffer.c
+F:	drivers/iio/imu/adis_trigger.c
 F:	include/linux/iio/imu/adis.h
 
 ANALOG DEVICES INC ADIS16460 DRIVER