iwlwifi: use long monitor timer to avoid un-necessary reload

For 5000 and 6000g2b series of devices, use long monitor timer to check
stuck tx queues.

.6000g2b series device, it is WiFi/BT combo device, there are some cases,
tx queues are not move for a period of time because the WiFi/BT coex.

.5000 series device, it is being reported firmware got reload more
often than necessary, so extend the timer to avoid un-necessary reload.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>