x86/fpu: Create 'union thread_xstate' helper for fpstate_init()

fpstate_init() only uses fpu->state, so pass that in to it.

This enables the cleanup we will do in the next patch.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/fpu/internal.h

@@ -29,7 +29,7 @@ extern void fpu__init_system(struct cpuinfo_x86 *c);
 
 extern void fpu__activate_curr(struct fpu *fpu);
 
-extern void fpstate_init(struct fpu *fpu);
+extern void fpstate_init(union thread_xstate *state);
 #ifdef CONFIG_MATH_EMULATION
 extern void fpstate_init_soft(struct i387_soft_struct *soft);
 #else