x86/fpu: Don't allocate fpu->state for swapper/0

Now that kthreads do not use FPU until they get executed, swapper/0
doesn't need to allocate fpu->state.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Riikonen <priikone@iki.fi>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Link: http://lkml.kernel.org/r/20150313182716.GB8249@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/xsave.c

@@ -680,8 +680,6 @@ void xsave_init(void)
 
 static inline void __init eager_fpu_init_bp(void)
 {
-	current->thread.fpu.state =
-	    alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
 	if (!init_xstate_buf)
 		setup_init_fpu_buf();
 }