iwlwifi: fix 64bit platform firmware loading

This patch fixes loading firmware from memory above 32bit.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Acked-by: Marcel Holtmann <holtmann@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>