pdfdocs: Fix 'make pdfdocs' failure for 'uio-howto.tmpl'

'make pdfdocs' failed for uio-howto.tmpl and reported errors of the form:
'document type does not allow element "varname" here; missing one of "remark", "synopsis", "fieldsynopsis", "literallayout", "programlisting", "screen", "para", "simpara", "bridgehead" start-tag'
and similar.
Fixed by adding '<para>' and '</para>' tags to a location that made sense, fixed the errors and the pdf looks OK in relevant ereas.

Signed-off-by: Sharon Dvir <sharon.dvir1@mail.huji.ac.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>