staging: dgnc: Fix checkpatch include warning

checkpatch.pl fix. Use #include <linux/uaccess.h> instead of
<asm/uaccess.h>

Signed-off-by: Kieron Browne <kieron.browne@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>