media: TDA1997x: fix tda1997x_remove()

TDA1997x driver tried to hold two values in a single variable:
device's "client data" pointer was first set to "sd" in
v4l2_i2c_subdev_init(), then it was overwritten explicitly
using dev_set_drvdata() with "state". This caused
tda1997x_remove() to fail badly.

Signed-off-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>