auxdisplay: charlcd: Drop unneeded initializers and switch to C99 style

For structure initializers the fields are 0 (or NULL) by default, so
there is no need to fill them explicitly. Besides that, much easier
to read when initializers use C99 style. Hence, convert to C99 style
as well.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>