iwlwifi: Remove IWL3945_DEBUG

IWL3945_DEBUG is pointless and obsolete. We already have an IWLWIFI_DEBUG
symbol, that needs to be set if we actually want to get 3945 debug (see
iwl-debug.h).
Thus, we can simply get rid of this symbol.

Signed-off-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>