If the acpi pm timer throws invalid data, clear pmtmr_ioport
so the pm timer won't accidentally be used.

This was found when using Xen where there is a acpi pm reported,
but gives bogus values, and other code was continuing to try
to use the pm timer after the initialization failed.

[jstultz: Catch additional failure and reword changelog message. ]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <1295027246-11110-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>