iwlwifi: adding parameter of fw_restart

This patch adds a module parameter of fw_restart which determine if
the uCode will be restarted or not in case of error.

Signed-off-by: Ester Kummer <ester.kummer@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>