auxdisplay: lcd2s: Fix memory leak in ->remove()

Once allocated the struct lcd2s_data is never freed.
Fix the memory leak by switching to devm_kzalloc().

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>