[PATCH] x86-64: Fix FPU corruption

This reverts an earlier patch that was found to cause FPU
state corruption. I think the corruption happens because
unlazy_fpu() can cause FPU exceptions and when it happens
after the current switch some processing would affect
the state in the wrong process.

Thanks to  Douglas Crosher and Tom Hughes for testing.

Cc: jbeulich@novell.com

Signed-off-by: Andi Kleen <ak@suse.de>