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

In the Linux kernel, the following vulnerability has been resolved: 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.