ACPI resource change triggers loss of serial ports

[Andy Whitcroft]

The recently merged change (in v3.14-rc6) to ACPI resource detection
(below) causes all zero length ACPI resources to be elided from the table:

  commit b355cee88e3b1a193f0e9a81db810f6f83ad728b
  Author: Zhang Rui <rui.zhang@xxxxxxxxx>
  Date:   Thu Feb 27 11:37:15 2014 +0800

    ACPI / resources: ignore invalid ACPI device resources

This change has caused a regression in (at least) serial port detection
for a number of machines (see LP#1313981 [1]).  These seem to represent
their IO regions (presumably incorrectly) as a zero length region.
Reverting the above commit restores these serial devices.

For Zhang's case I wonder if this check could be tightened up to cover
only the zero base, something like the (untested) patch below.

-apw

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1313981