[MIPS] Fix errors detected by "make headers_check"

* export asm/sgidefs.h
* include asm/isadep.h only if in kernel
* do not export contents of asm/timex.h and asm/user.h

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/user.h b/include/asm-mips/user.h
index 89bf8b4..61f2a09 100644
--- a/include/asm-mips/user.h
+++ b/include/asm-mips/user.h
@@ -8,6 +8,8 @@
 #ifndef _ASM_USER_H
 #define _ASM_USER_H
 
+#ifdef __KERNEL__
+
 #include <asm/page.h>
 #include <asm/reg.h>
 
@@ -55,4 +57,6 @@
 #define HOST_DATA_START_ADDR	(u.start_data)
 #define HOST_STACK_END_ADDR	(u.start_stack + u.u_ssize * NBPG)
 
+#endif /* __KERNEL__ */
+
 #endif /* _ASM_USER_H */