auxdisplay: hd44780: Fix potential memory leak in hd44780_remove()

hd44780_probe() allocates a memory chunk for hd with kzalloc() and
makes "lcd->drvdata->hd44780" point to it. When we call hd44780_remove(),
we should release all relevant memory and resource. But "lcd->drvdata
->hd44780" is not released, which will lead to a memory leak.

We should release the "lcd->drvdata->hd44780" in hd44780_remove() to fix
the memory leak bug.

Fixes: 718e05ed92ec ("auxdisplay: Introduce hd44780_common.[ch]")
Reviewed-by: Andy Shevchenko <[e-mail]>
Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Jianglei Nie <[e-mail]>
Signed-off-by: Miguel Ojeda <[e-mail]>

drivers/auxdisplay/hd44780.c

···
 static int hd44780_remove(struct platform_device *pdev)
 {
 	struct charlcd *lcd = platform_get_drvdata(pdev);
+	struct hd44780_common *hdc = lcd->drvdata;
 
 	charlcd_unregister(lcd);
+	kfree(hdc->hd44780);
 	kfree(lcd->drvdata);
 
 	kfree(lcd);