x86: Dynamically increase early_res array size

Use early_res_count to track the num, and use find_e820 to get a new
buffer, then copy from the old to the new one.

Also, clear early_res to prevent later invalid usage.

-v2 _check_and_double_early_res should take new start

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-14-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>