[media] diff-v4l.rst: Make capabilities table fit in LaTeX

[media] diff-v4l.rst: Make capabilities table fit in LaTeX

This table has several troubles:
	- a duplicated "struct" on its name;
	- a reference to a V4L version 1 struct that will never
	  point to something (as we got rid of V4L1 API a long
	  time ago);
	- misses hints for LaTeX output (column size and longtable
	  style).

Fix them.

It should be noticed that the first column of this table is
not aligned with the rest. I suspect that this is a bug at
the flat-table extension.

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