iwlwifi: use long monitor timer for 5300 series

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

This modification apply to all the 5000 series including 5300 and others.

Cc: stable@kernel.org [2.6.35]
Reported-by: drago01 <drago01@gmail.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>