Input: tps6507x-ts - simplify function return logic

The invoked function already returns zero on success or a negative
errno code so there is no need to open code the logic in the caller.

This also fixes the following make coccicheck warning:

drivers/input/touchscreen/tps6507x-ts.c:57:5-8: WARNING: end returns can be simplified
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/tps6507x-ts.c

@@ -50,14 +50,7 @@ struct tps6507x_ts {
 
 static int tps6507x_read_u8(struct tps6507x_ts *tsc, u8 reg, u8 *data)
 {
-	int err;
-
-	err = tsc->mfd->read_dev(tsc->mfd, reg, 1, data);
-
-	if (err)
-		return err;
-
-	return 0;
+	return tsc->mfd->read_dev(tsc->mfd, reg, 1, data);
 }
 
 static int tps6507x_write_u8(struct tps6507x_ts *tsc, u8 reg, u8 data)