[ARM] 4483/1: ns9xxx: fix three sparse warnings: symbol 'xyz' was not declared.

make ns9xxx_ack_irq_functions static and add one include to get declarations
for ns9xxx_map_io and ns9xxx_init_machine.

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