ACPI: Make acpi_skip_timer_override cover all source_irq==0 cases

Currently when acpi_skip_timer_override is set, it only cover the
(source_irq == 0 && global_irq == 2) cases. While there is also
platform which need use this option and its global_irq is not 2.
This patch will extend acpi_skip_timer_override to cover all
timer overriding cases as long as the source irq is 0.

This is the first part of a fix to kernel bug bugzilla 40002:
	"IRQ 0 assigned to VGA"
https://bugzilla.kernel.org/show_bug.cgi?id=40002



Reported-and-tested-by: Szymon Kowalczyk <fazerxlo@o2.pl>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>