nios2: Add types.h header required for __u32 type

Reported by the header checker (CONFIG_HEADERS_CHECK=y):

  CHECK   usr/include/asm/ (31 files)
./usr/include/asm/ptrace.h:77: found __[us]{8,16,32,64} type without #include <linux/types.h>

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Acked-by: Ley Foon Tan <lftan@altera.com>

arch/nios2/include/uapi/asm/ptrace.h

@@ -14,6 +14,8 @@
 
 #ifndef __ASSEMBLY__
 
+#include <linux/types.h>
+
 /*
  * Register numbers used by 'ptrace' system call interface.
  */