iwl3945: use rx queue management infrastructure from iwlcore

This patch uses rx queue alloc free and reset function from iwlcore.
This should fix the regression reported by Kalle Valo.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>