gpio: add Intel Moorestown Platform Langwell chip gpio driver

The Langwell chip is the IO hub for Intel Moorestown platform which has a
64-pin gpio block device inside.  It is exposed as a dedicated PCI device.
 We use it to control outside peripheral as well as to do IRQ demuxing.
The gpio block uses MSI to send level type interrupt to IOAPIC.

Signed-off-by: Alek Du <alek.du@intel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>