auxdisplay: ht16k33: Switch to use line display character mapping

Since line display library supports necessary bits to map the characters
(if required), switch this driver to use that.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>