The syscall pages are written to be used also as man-pages.

However, they don't match the format used by kernel-doc
generated pages from DocBook. Rewrite them to match it.

One side effect is that now all such pages at the book
will have the same format, reducing the format differences
between DVB and the other parts of the book.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>