debugfs: set no_llseek in DEFINE_DEBUGFS_ATTRIBUTE

In DEFINE_DEBUGFS_ATTRIBUTE() macro, since we use nonseekable_open() to
open, we should use no_llseek() to seek, not generic_file_llseek().

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>