auxdisplay: arm-charlcd: convert to use device managed APIs

auxdisplay: arm-charlcd: convert to use device managed APIs

The current probe function of the driver is implemented by using
plain old APIs. As Geert noted, one of the error paths has a mistake
that may lead to a wrong call. Instead of targeting that particular
issue, convert the driver to use device managed APIs altogether.
It's not needed per se (driver can never be removed once loaded),
but it simplifies coding and error handling.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/r/CAMuHMdVquNEoxRQkcBEH0nC+CDuib6o0H6m3CBk3ZN2267LpQw@mail.gmail.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>