x86 thermal: Disable power limit notification interrupt by default

The package power limit notification interrupt is primarily for
system diagnosis, and should not be blindly enabled on every
system by default -- particuarly since Linux does nothing in the
handler except count how many times it has been called...

Add a new kernel cmdline parameter "int_pln_enable" for situations where
users want to oberve these events via existing system counters:

$ grep TRM /proc/interrupts

$ grep . /sys/devices/system/cpu/cpu*/thermal_throttle/*

https://bugzilla.kernel.org/show_bug.cgi?id=36182

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6e3b18a..a7a1f34 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1158,6 +1158,8 @@
 	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
 			Format: <irq>
 
+	int_pln_enable  [x86] Enable power limit notification interrupt
+
 	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
 		on
 			Enable intel iommu driver.