UAPI: fix tools/vm/page-types.c

Fix tools/vm/page-types.c to use the UAPI variant of linux/kernel-page-flags.h
lest the following error appear:

In file included from page-types.c:38:0:
../../include/linux/kernel-page-flags.h:4:42: fatal error:
uapi/linux/kernel-page-flags.h: No such file or directory

Reported-by: Daniel Hazelton <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Reviewed-by: Fengguang Wu <[e-mail]>
Tested-by: Daniel Hazelton <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

tools/vm/page-types.c

···
 #include <sys/mount.h>
 #include <sys/statfs.h>
 #include "../../include/uapi/linux/magic.h"
-#include "../../include/linux/kernel-page-flags.h"
+#include "../../include/uapi/linux/kernel-page-flags.h"
 
 
 #ifndef MAX_PATH