x86: syscalls.h: remove asmlinkage from declaration of sys_rt_sigreturn()

Impact: cleanup

asmlinkage for sys_rt_sigreturn() no longer exists in arch/x86/kernel/signal.c.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/syscalls.h

@@ -82,7 +82,7 @@ asmlinkage long sys_iopl(unsigned int, struct pt_regs *);
 /* kernel/signal_64.c */
 asmlinkage long sys_sigaltstack(const stack_t __user *, stack_t __user *,
 				struct pt_regs *);
-asmlinkage long sys_rt_sigreturn(struct pt_regs *);
+long sys_rt_sigreturn(struct pt_regs *);
 
 /* kernel/sys_x86_64.c */
 asmlinkage long sys_mmap(unsigned long, unsigned long, unsigned long,