x86: split e820 reserved entries record to late v4

this one replaces:

| commit a2bd7274


| Author: Yinghai Lu <yhlu.kernel@gmail.com>
| Date:   Mon Aug 25 00:56:08 2008 -0700
|
|    x86: fix HPET regression in 2.6.26 versus 2.6.25, check hpet against BAR, v3

v2: insert e820 reserve resources before pnp_system_init
v3: fix merging problem in tip/x86/core
v4: address Linus's review about comments and condition in _late()

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