staging: lustre: declare some functions as static

Declare these functions as static:
llog_alloc_handle() is used in llog_open() only.
llog_free_handle() is used in llog_close() only.

Signed-off-by: Zheng Di <zhengdi05@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>