iwlwifi: Adjusting PLCP error threshold for 1000 NIC

While testing the station with the NIC 1000 family, it is found that
the plcp error can easily exceed 50 value in 100mSecs.  This creates
unneccessary radio reset/tuning.  This patch raises the PLCP error
threshold of the NIC 1000 from 50 to 200 error count.

Signed-off-by: Trieu 'Andrew' Nguyen <trieux.t.nguyen@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>