x86: fix setup.c printk format warning

Fix setup.c printk format warning:

linux-next-20080605/arch/x86/kernel/setup.c: In function 'setup_per_cpu_areas':
linux-next-20080605/arch/x86/kernel/setup.c:173: warning: format '%lu' expects type 'long unsigned int', but argument 2 has type 'ssize_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>