iio: adc: ad_sigma_delta: use u8 instead of uint8_t

iio: adc: ad_sigma_delta: use u8 instead of uint8_t

Replace uint8_t with u8 in the ad_sigma_delta driver.

Technically, uint8_t comes from the C standard library, while u8 is a
Linux kernel type. Since we don't use the C standard library in the
kernel, we should use the kernel types instead.

There is also one instance where int64_t is replaced with s64.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250701-iio-adc-ad7173-add-spi-offload-support-v3-3-42abb83e3dac@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>