iio: imu: adis: Add DIAG_STAT register

iio: imu: adis: Add DIAG_STAT register

Some devices may have more than 16 bits of status. This patch allows the
user to specify the size of the DIAG_STAT register. It defaults to 2 if
not specified. This is mainly for backward compatibility.

Co-developed-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Co-developed-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Co-developed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Robert Budai <robert.budai@analog.com>
Link: https://patch.msgid.link/20250217105753.605465-4-robert.budai@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>