media: Fix RTL2832 not depending on REGMAP_I2C

Prevents this compile time error:

ERROR: modpost: "__regmap_init_i2c" [drivers/media/dvb-frontends/rtl2832.ko] undefined!

Signed-off-by: Maxim Plotnikov <wgh@torlan.ru>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>