In order to be more particular in names, rename to_priv() macro
to charlcd_to_priv().

No functional change intended.
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>