ACPI: kernel-parameters.txt : Add intel_idle.max_cstate

Add missing intel_idle.max_cstate in kernel-parameters.txt

Signed-off-by Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 81c287f..c6a56d8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1035,6 +1035,11 @@
 			By default, super page will be supported if Intel IOMMU
 			has the capability. With this option, super page will
 			not be supported.
+
+	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
+			0	disables intel_idle and fall back on acpi_idle.
+			1 to 6	specify maximum depth of C-state.
+
 	intremap=	[X86-64, Intel-IOMMU]
 			on	enable Interrupt Remapping (default)
 			off	disable Interrupt Remapping