Staging: iio: meter: Remove explicit NULL comparison

This patch removes explicit NULL comparison and replaces it with
its shorter form. Detected with coccinelle.

@replace_rule@
expression e;
@@

-e == NULL
+ !e

Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/iio/meter/ade7758_core.c

@@ -833,7 +833,7 @@ static int ade7758_probe(struct spi_device *spi)
 	if (!st->rx)
 		return -ENOMEM;
 	st->tx = kcalloc(ADE7758_MAX_TX, sizeof(*st->tx), GFP_KERNEL);
-	if (st->tx == NULL) {
+	if (!st->tx) {
 		ret = -ENOMEM;
 		goto error_free_rx;
 	}

drivers/staging/iio/meter/ade7758_ring.c

@@ -132,7 +132,7 @@ int ade7758_configure_ring(struct iio_dev *indio_dev)
 						 indio_dev,
 						 "ade7759_consumer%d",
 						 indio_dev->id);
-	if (indio_dev->pollfunc == NULL) {
+	if (!indio_dev->pollfunc) {
 		ret = -ENOMEM;
 		goto error_iio_kfifo_free;
 	}

drivers/staging/iio/meter/ade7758_trigger.c

@@ -66,7 +66,7 @@ int ade7758_probe_trigger(struct iio_dev *indio_dev)
 	st->trig = iio_trigger_alloc("%s-dev%d",
 					spi_get_device_id(st->us)->name,
 					indio_dev->id);
-	if (st->trig == NULL) {
+	if (!st->trig) {
 		ret = -ENOMEM;
 		goto error_ret;
 	}