[media] coda: include header for memcpy

coda_h264_padding uses memcpy, we should include string.h for that.

Reported-by: Ian Jamison <ian.dev@arkver.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>