media: camera-sensor.rst: fix a doc build warning

Documentation/driver-api/media/camera-sensor.rst:123: WARNING: Inline literal start-string without end-string.

There's a missing blank line over there.

Link: https://lore.kernel.org/linux-media/c326774ad841b905c3b2925e5f8f509d29fb4c6f.1599656828.git.mchehab+huawei@kernel.org


Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>