[nrf fromlist] drivers: adc: nrfx_saadc: Fix for negative samples correction

Increment pointer only when channel was selected.

Upstream PR #: 94705

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

Author: jaz1-nordic

drivers/adc/adc_nrfx_saadc.c

@@ -575,8 +575,8 @@ static void correct_single_ended(const struct adc_sequence *sequence, nrf_saadc_
 				} else if (*sample < 0) {
 					*sample = 0;
 				}
+				sample++;
 			}
-			sample++;
 		}
 	}
 }