drivers: adc: siwx91x: Return raw ADC value

Instead of returning a converted ADC reading, return the
raw ADC sample. Conversion is left to the user based on
the selected ADC mode (single-ended or differential).

Signed-off-by: Sai Santhosh Malae <[email protected]>
(cherry picked from commit 78f47a3)
Upstream-status: available

Author: smalae

drivers/adc/adc_silabs_siwx91x.c

@@ -333,12 +333,6 @@ int16_t adc_siwx91x_read_data(const struct device *dev)
 		adc_temp = 0;
 	}
 
-	if (adc_temp >= 2048) {
-		adc_temp = adc_temp - 2048;
-	} else {
-		adc_temp = adc_temp + 2048;
-	}
-
 	return adc_temp;
 }