x86/fpu: Rename save_xstate_sig() to copy_fpstate_to_sigframe()

Standardize the naming of save_xstate_sig() by renaming it to
copy_fpstate_to_sigframe(): this tells us at a glance that
the function copies an FPU fpstate to a signal frame.

This naming also follows the naming of copy_fpregs_to_fpstate().

Don't put 'xstate' into the name: since this is a generic name,
it's expected that the function is able to handle xstate frames
as well, beyond legacy frames.

xstate used to be the odd case in the x86 FPU code - now it's the
common case.

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>
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index da96b0c..58c274d 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -523,7 +523,7 @@
 /*
  * Signal frame handlers...
  */
-extern int save_xstate_sig(void __user *buf, void __user *fx, int size);
+extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fx, int size);
 extern int __restore_xstate_sig(void __user *buf, void __user *fx, int size);
 
 static inline int xstate_sigframe_size(void)