Introduce support for triggering interrupts on both rising and falling
edge.

This feature requires version 3 or newer of the IP, a version check is
done when triggering on both edges is requested.
Signed-off-by: NRichard Röjfors <richard.rojfors@pelagicore.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>