docs: misc-devices/bh1770glc.txt: convert to ReST

- Adjust document title markup;
- use list markups;
- Adjust identations to display properly at ReST output.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/58ba712524318d03b3196bba33cb409472b4807d.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>