[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/timex.h b/include/asm-mips/timex.h
index 98aa737..b80de8e 100644
--- a/include/asm-mips/timex.h
+++ b/include/asm-mips/timex.h
@@ -8,6 +8,8 @@
 #ifndef _ASM_TIMEX_H
 #define _ASM_TIMEX_H
 
+#ifdef __KERNEL__
+
 #include <asm/mipsregs.h>
 
 /*
@@ -51,4 +53,6 @@
 	return read_c0_count();
 }
 
+#endif /* __KERNEL__ */
+
 #endif /*  _ASM_TIMEX_H */