[nrf fromlist] drivers: adc: nrfx: fix for negative samples in single-mode

We need to check value of the sample not the pointer.

Upstream PR #: 91368

Signed-off-by: Jakub Zymelka <[email protected]>

Author: jaz1-nordic

drivers/adc/adc_nrfx_saadc.c

@@ -541,7 +541,7 @@ static inline void single_ended_channel_cut_negative_sample(uint16_t channel_bit
 							    uint8_t single_ended_channels,
 							    int16_t **sample)
 {
-	if ((channel_bit & single_ended_channels) && (*sample < 0)) {
+	if ((channel_bit & single_ended_channels) && (**sample < 0)) {
 		**sample = 0;
 	}