[PATCH] parport: DEBUG_PARPORT build fix

Add missing "struct" keyword preventing compilation with DEBUG_PARPORT
defined.  Also add some "const".

Signed-off-by: Marko Kohtala <marko.kohtala@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>