iio: adc: twl4030-madc: Remove set but unused variables 'len'

Fixes the following W=1 kernel build warning(s):

 drivers/iio/adc/twl4030-madc.c: In function ‘twl4030_madc_threaded_irq_handler’:
 drivers/iio/adc/twl4030-madc.c:475:9: warning: variable ‘len’ set but not used [-Wunused-but-set-variable]
 475 | int i, len, ret;
 | ^~~

Cc: Sebastian Reichel <sre@kernel.org>
Cc: J Keerthy <j-keerthy@ti.com>
Cc: Mikko Ylinen <mikko.k.ylinen@nokia.com>
Cc: Amit Kucheria <amit.kucheria@canonical.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/twl4030-madc.c

@@ -472,7 +472,7 @@ static irqreturn_t twl4030_madc_threaded_irq_handler(int irq, void *_madc)
 	struct twl4030_madc_data *madc = _madc;
 	const struct twl4030_madc_conversion_method *method;
 	u8 isr_val, imr_val;
-	int i, len, ret;
+	int i, ret;
 	struct twl4030_madc_request *r;
 
 	mutex_lock(&madc->lock);
@@ -504,7 +504,7 @@ static irqreturn_t twl4030_madc_threaded_irq_handler(int irq, void *_madc)
 			continue;
 		method = &twl4030_conversion_methods[r->method];
 		/* Read results */
-		len = twl4030_madc_read_channels(madc, method->rbase,
+		twl4030_madc_read_channels(madc, method->rbase,
 					   r->channels, r->rbuf, r->raw);
 		/* Free request */
 		r->result_pending = false;
@@ -525,7 +525,7 @@ static irqreturn_t twl4030_madc_threaded_irq_handler(int irq, void *_madc)
 			continue;
 		method = &twl4030_conversion_methods[r->method];
 		/* Read results */
-		len = twl4030_madc_read_channels(madc, method->rbase,
+		twl4030_madc_read_channels(madc, method->rbase,
 					   r->channels, r->rbuf, r->raw);
 		/* Free request */
 		r->result_pending = false;