iwlwifi: add ucode loaders for iwl5000

This patch adds ucode initialization handler and functions to load
ucode for iwl5000 NIC.

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>