staging: iio: tsl2x7x_core: Fix sparse warning

Silences the following warning:
drivers/staging/iio/light/tsl2x7x_core.c:553:70:
warning: Using plain integer as NULL pointer

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: J. August Brenner <jbrenner@taosinc.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/light/tsl2x7x_core.c

@@ -550,7 +550,7 @@ prox_poll_err:
 static void tsl2x7x_defaults(struct tsl2X7X_chip *chip)
 {
 	/* If Operational settings defined elsewhere.. */
-	if (chip->pdata && chip->pdata->platform_default_settings != 0)
+	if (chip->pdata && chip->pdata->platform_default_settings)
 		memcpy(&(chip->tsl2x7x_settings),
 			chip->pdata->platform_default_settings,
 			sizeof(tsl2x7x_default_settings));