x86: Put 'nopat' in kernel-parameters

Add missing 'nopat' boot option into
Documentation/kernel-parameters.txt.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
LKML-Reference: <alpine.LNX.2.00.1001181703560.30977@pobox.suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/kernel-parameters.txt

@@ -1729,6 +1729,9 @@ and is between 256 and 4096 characters. It is defined in the file
 	nomfgpt		[X86-32] Disable Multi-Function General Purpose
 			Timer usage (for AMD Geode machines).
 
+	nopat		[X86] Disable PAT (page attribute table extension of
+			pagetables) support.
+
 	norandmaps	Don't use address space randomization.  Equivalent to
 			echo 0 > /proc/sys/kernel/randomize_va_space