iwlwifi-5000: add iwl 5000 shared memory handlers

This patch fills the needed handlers for shared memory for
iwl 5000 family

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>