x86, memblock: Add memblock_x86_find_in_range_size()

size is returned according free range.
Will be used to find free ranges for early_memtest and memory corruption check

Do not mess it up with lib/memblock.c yet.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>