ASIC3 driver

This is a patch for the Compaq ASIC3 multi function chip, found in many
PDAs (iPAQs, HTCs...).

It is a simplified version of Paul Sokolovsky's first proposal [1].  With
this code, it is basically a GPIO and IRQ expander.  My plan is to add more
features once this patch gets reviewed and accepted.

[1] http://lkml.org/lkml/2007/5/1/46

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Cc: Paul Sokolovsky <pmiscml@gmail.com>
Cc: Ben Dooks <ben@trinity.fluff.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>