panel-s6e8aa0.c: add contrast module. Original implementation from morfic

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
[PATCH] lib: Improve the performance of string.c

The performance of memcpy and memmove of the general version is
very inefficient, this patch improves them.

Taken from Arne Coucheron