autofs: move inclusion of linux/limits.h to uapi

linux/limits.h should be included by uapi instead of linux/auto_fs.h
so as not to cause compile error in userspace.

 # cat << EOF > ./test1.c
 > #include <stdio.h>
 > #include <linux/auto_fs.h>
 > int main(void) {
 >     return 0;
 > }
 > EOF
 # gcc -Wall -g ./test1.c
 In file included from ./test1.c:2:0:
 /usr/include/linux/auto_fs.h:54:12: error: 'NAME_MAX' undeclared here (not in a function)
   char name[NAME_MAX+1];
             ^

Link: http://lkml.kernel.org/r/20160812024856.12352.24092.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <ikent@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/auto_fs.h

@@ -10,7 +10,6 @@
 #define _LINUX_AUTO_FS_H
 
 #include <linux/fs.h>
-#include <linux/limits.h>
 #include <linux/ioctl.h>
 #include <uapi/linux/auto_fs.h>
 #endif /* _LINUX_AUTO_FS_H */

include/uapi/linux/auto_fs.h

@@ -12,6 +12,7 @@
 #define _UAPI_LINUX_AUTO_FS_H
 
 #include <linux/types.h>
+#include <linux/limits.h>
 #ifndef __KERNEL__
 #include <sys/ioctl.h>
 #endif /* __KERNEL__ */