Input: move map_to_7segment.h to include/linux

The map_to_7segment.h provides generic 7segment LED mappings and is
designed to be used by other drivers.  Moving it to common area will
make it more usable.  Also exporting it to userspace will help users
of sysfs interface.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Henk Vergonet <henk.vergonet@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>