iio: accel: bma180: use stack allocated buffer for scan

iio: accel: bma180: use stack allocated buffer for scan

Move the scan struct to the stack instead of being in the driver state
struct. The buffer is only used in a single function and does not need
to be DMA-safe so it does not need to exist outside of that function's
scope.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250721-iio-use-more-iio_declare_buffer_with_ts-v2-1-f8fb11b8add8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>