iio: adc: ad4000: don't use shift_right()

iio: adc: ad4000: don't use shift_right()

Drop use of shift_right() macro for unsigned value. The shift_right()
macro is intended for signed values and is not needed for unsigned
values.

This was found by a static analysis tool [1].

Link: https://github.com/analogdevicesinc/linux/pull/2831/files#diff-c14a34a6492576d22e7192cc0f61ad0083190aeb627191596fe12462f0c6f21aR557
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250702-iio-adc-ad4000-don-t-use-shift_right-v1-1-041c2d6c3950@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>