Staging: iio: accel: sca3000: Fixed NULL comparison style

The variable u8 **rx_p, is a pointer-to-pointer and hence the check
should
be "if (!*rx_p)" and not "if (!rx_p)".
In the earlier version, checkpatch.pl gave the following check, which
was incorrect:
CHECK: Comparison to NULL could be written "!rx_p"
+       if (*rx_p == NULL) {

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/accel/sca3000_ring.c

@@ -48,7 +48,7 @@ static int sca3000_read_data(struct sca3000_state *st,
 		}
 	};
 	*rx_p = kmalloc(len, GFP_KERNEL);
-	if (*rx_p == NULL) {
+	if (!*rx_p) {
 		ret = -ENOMEM;
 		goto error_ret;
 	}