[ARM] 4487/1: ns9xxx: complete definition of GPIO related registers

I changed the naming to be more obvious---unfortunately the HRM
doesn't specify these.

Moreover the numbering is changed to be zero indexed as this is more
natural.

Adjust all callers.

Signed-off-by: Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>