ARM: pxa: fix build error for GPIO_bit()

arch/arm/mach-pxa/spitz_pm.c: In function ‘spitz_presuspend’:
arch/arm/mach-pxa/spitz_pm.c:112:2: error: implicit declaration of
function ‘GPIO_bit’
make[1]: *** [arch/arm/mach-pxa/spitz_pm.o] Error 1

GPIO_bit() is moved into <linux/gpio-pxa.h>.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>