buildroot

motion: fix config file location

Install the motion.config file were the program expects it to be. From
the motion source code:

snprintf(filename, PATH_MAX, "%s/motion/motion.conf", sysconfdir);

Signed-off-by: Christopher McCrory <chrismcc@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>