acpi, memory-hotplug: parse SRAT before memblock is ready fix

acpi, memory-hotplug: parse SRAT before memblock is ready fix

alnoconfig complains:
arch/x86/kernel/setup.c: In function `setup_arch':
arch/x86/kernel/setup.c:917: error: implicit declaration of function `early_parse_srat'

because early_parse_srat is not declared for !CONFIG_ACPI. Moreover it
is defined only for CONFIG_ACPI_NUMA.

I am not sure what is the correct way to fix this but I guess that
providing an empty definition for !CONFIG_ACPI_NUMA is OK.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>