media: v4l uAPI docs: adjust some tables for PDF output

On tests with Spinx 1.4, some tables are still writing text
outside cells. Adjust those tables.

PS.: As this was revisited several times, I suspect that this
will only be fully fixed if we add tabularcolumns to all tables
at the V4L2 part of the book.

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