doc-rst: linux_tv: fix some warnings due to '*'

Unescaped * causes warnings on Sphinx.

Add an escape at hist-v4l2 occurrences.

At libv4l-introduction, the best is do declare the function
prototypes as C code.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2 files changed