staging: lustre: include header with local ptlrpc declarations

Include the header with declarations of variables that are shared between
several sources in ptlrpc module into the appropriate source files.

Signed-off-by: Anton Gerasimov <anton.gerasimov@openmailbox.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>