x86/fpu: Remove duplicate copy_fpstate_to_sigframe() prototype

The function prototype of copy_fpstate_to_sigframe() is declared twice in

  0ae67cc3 ("x86/fpu: Remove internal.h dependency from fpu/signal.h").

Remove one of them.

 [ bp: Massage ]

Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211209015550.51916-1-zhangshaokun@hisilicon.com