[ARM] 3364/1: [cleanup] warning fix - definitions for enable_hlt and disable_hlt

Patch from Ben Dooks

The enable_hlt and disable_hlt should be declared in
include/asm/setup.h. This fixes sparse errors from
arch/arm/kernel/process.c

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>