[media] si2157: add copyright and license

Add copyright and license for each file.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --cc drivers/media/tuners/si2157.c
Simple merge

diff --cc drivers/media/tuners/si2157.h
Simple merge

diff --cc drivers/media/tuners/si2157_priv.h
Simple merge