staging/lustre: Remove unused target_print_req()

This is a server-side request printing function, so we don't
really need it on the client.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>