sparc32: fix sparse warning in ptrace_32.c

Fix following warning:
ptrace_32.c:444:16: warning: symbol 'syscall_trace' was not declared. Should it be static?

Add declaration in kernel.h

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/kernel/ptrace_32.c b/arch/sparc/kernel/ptrace_32.c
index 896ba7c..a331fdc 100644
--- a/arch/sparc/kernel/ptrace_32.c
+++ b/arch/sparc/kernel/ptrace_32.c
@@ -26,6 +26,8 @@
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
 
+#include "kernel.h"
+
 /* #define ALLOW_INIT_TRACING */
 
 /*