[media] si2157: Add support for Si2158 chip

Add support for Si2158 A20 chip.

Signed-off-by: Olli Salonen <olli.salonen@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
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