docs: misc-devices/c2port.txt: convert to ReST format

- Use copyright symbol;
- use title markups;
- adjust indentation;
- mark literal blocks as such.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
[jc: reverted |copy| change]
Link: https://lore.kernel.org/r/b3b2f3f58a9a33f9e8526d4fa36bee305ea4da38.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>