wifi: ath9k: do not submit zero bytes to the entropy pool

wifi: ath9k: do not submit zero bytes to the entropy pool

In 'ath_cmn_process_fft()', it doesn't make too much sense to
add zero bytes in attempt to improve randomness. So swap calls
to 'memset()' and 'add_device_randomness()' to feed the pool
with actual FFT results rather than zeroes. Compile tested only.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Fixes: 2aa56cca3571 ("ath9k: Mix the received FFT bins to the random pool")
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20250123141058.1696502-1-dmantipov@yandex.ru
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>