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: 718e05ed ("auxdisplay: Introduce hd44780_common.[ch]")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>