x86/sigreturn: use SYSCALL_DEFINE0

All definitions of syscalls in x86 except for those patched here have
already been using the appropriate SYSCALL_DEFINE*.

Signed-off-by: Michael Tautschnig <tautschn@amazon.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jaswinder Singh <jaswinder@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: x86@kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

arch/x86/kernel/signal.c

@@ -25,6 +25,7 @@
 #include <linux/user-return-notifier.h>
 #include <linux/uprobes.h>
 #include <linux/context_tracking.h>
+#include <linux/syscalls.h>
 
 #include <asm/processor.h>
 #include <asm/ucontext.h>
@@ -601,7 +602,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
  * Do a signal return; undo the signal stack.
  */
 #ifdef CONFIG_X86_32
-asmlinkage long sys_sigreturn(void)
+SYSCALL_DEFINE0(sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
 	struct sigframe __user *frame;
@@ -633,7 +634,7 @@ badframe:
 }
 #endif /* CONFIG_X86_32 */
 
-asmlinkage long sys_rt_sigreturn(void)
+SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe __user *frame;