x86: make e820_saved have update from setup_data

seperate reserve_setup_data into e820_reserved_setup_data,
and reserve_early_setup_data.

So could use e820_reserved_setup_data to backup e820 with setup_data.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Bernhard Walle <bwalle@suse.de>
Cc: Ying Huang <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>