x86, fpu: make eagerfpu= boot param tri-state

Add the "eagerfpu=auto" (that selects the default scheme in
enabling eagerfpu) which can override compiled-in boot parameters
like "eagerfpu=on/off" (that force enable/disable eagerfpu).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-5-git-send-email-suresh.b.siddha@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e8f7faa..46a6a82 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1834,8 +1834,10 @@
 			enabling legacy floating-point and sse state.
 
 	eagerfpu=	[X86]
-			on	enable eager fpu restore (default for xsaveopt)
+			on	enable eager fpu restore
 			off	disable eager fpu restore
+			auto	selects the default scheme, which automatically
+				enables eagerfpu restore for xsaveopt.
 
 	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
 			wfi(ARM) instruction doesn't work correctly and not to