media: Adjust column width for pdfdocs

The column width specifiers added in commit 8d0e3fc6 ("media:
Add 2-10-10-10 RGB formats") don't suffice for column 1 and too
wide for column 2.

Adjust them to get a good looking table.

Fixes: 8d0e3fc6 ("media: Add 2-10-10-10 RGB formats")
Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Link: https://lore.kernel.org/r/f94e3ada-212c-eef7-9e7b-03760bb29521@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>