uapi: Add <linux/map_to_14segment.h>

Add a header file providing translation primitives and tables for the
conversion of (ASCII) characters to a 14-segments notation, as used by
14-segment alphanumeric displays.

This follows the spirit of include/uapi/linux/map_to_7segment.h.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>