Staging: heci: fix the problem that file_ext->state should be protected by device_lock

While access file_ext->state, we should use device_lock to protect it. The
original codes miss this in some places.

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>