iwlwifi: Support for uCode without init and bsm section

This patch enables loading fw w/o init and bsm section. It also provides
general cleanup of the rutine.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>