iwlwifi: implement iwl_debug_report_frame for iwlagn

The old version of this code was copied from 3945 and never updated. This patch
cleans up structs that do not apply and accounts for other changes from
3945->iwlagn (e.g., PHY info can come in a separate cmd response from the
ucode.)

Signed-off-by: Daniel Halperin <daniel.c.halperin@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>