Staging: lustre: Used "linux" instead of "asm"

This patch fixes "Use #include <linux/uaccess.h> instead of
<asm/uaccess.h"> checkpatch.pl warning in dir.c

Signed-off-by: aybuke ozdemir <aybuke.147@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>