gpio: qpnp-gpio: Update driver to match new hardware specification

The software / hardware interface for the qpnp gpio block has
changed. Update the driver to match the new interface. Also
improve error handling where possible. No change in the feature
set is introduced by this modification.

Change-Id: I9d4c6a10296de86e3cf6f3b4c2006ed81353f58f
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>