x86: rename setup_32.c to setup.c

and let 64 bit use that instead of setup_64.c

[ mingo@elte.hu ]

x86: build fix

fix:

arch/x86/kernel/setup.c: In function ‘setup_arch':
arch/x86/kernel/setup.c:561: error: implicit declaration of function ‘efi_reserve_early'

and:

arch/x86/kernel/setup.c:766: error: implicit declaration of function 'init_cpu_to_node'

and:

arch/x86/kernel/setup.c:676: warning: operation on 'max_pfn_mapped' may be undefined

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>