staging: iio: ad5933: Correct settling cycles encoding per datasheet

The AD5933 datasheet (Table 13) lists the maximum cycles to be 0x7FC
(2044).

Clamp the user input to the maximum effective value of 0x7FC cycles.

Fixes: f94aa354 ("iio: impedance-analyzer: New driver for AD5933/4 Impedance Converter, Network Analyzer")
Cc: stable@vger.kernel.org
Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Link: https://patch.msgid.link/20250420013009.847851-1-gshahrouzi@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>