iwlwifi: Rx handlers common use for 4965 and 5000

This patch moves Rx handlers from iwl 4965 only use to common use along
with iwl 5000, thus enables Rx path to iwl 5000.

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>