auxdisplay: lcd2s: Use proper API to free the instance of charlcd object

While it might work, the current approach is fragile in a few ways:
- whenever members in the structure are shuffled, the pointer will be wrong
- the resource freeing may include more than covered by kfree()

Fix this by using charlcd_free() call instead of kfree().

Fixes: 8c9108d0 ("auxdisplay: add a driver for lcd2s character display")
Cc: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

drivers/auxdisplay/lcd2s.c

@@ -336,7 +336,7 @@ static int lcd2s_i2c_probe(struct i2c_client *i2c,
 	return 0;
 
 fail1:
-	kfree(lcd);
+	charlcd_free(lcd2s->charlcd);
 	return err;
 }
 
@@ -345,7 +345,7 @@ static int lcd2s_i2c_remove(struct i2c_client *i2c)
 	struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c);
 
 	charlcd_unregister(lcd2s->charlcd);
-	kfree(lcd2s->charlcd);
+	charlcd_free(lcd2s->charlcd);
 	return 0;
 }