iwlwifi: move HW device registration

This patch moves the HW device registration from the iwl-4965.c file, which
implies a HW specific support, to a more general location.

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>