iwlwifi: remove iwl4965_nic_start function

This patch moves the contant of iwl4965_nic_start to the only place it is
being used.

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>