iwlwifi: code cleanup for connectivity recovery

Split the connectivity check and recovery routine into separated
functions based on the types
   1. iwl_good_ack_health() - check for ack count
   2. iwl_good_plcp_health() - check for plcp error

Based on the type of errors being detected, different recovery methods
will be used to bring the system back to normal operational state.

Because different NIC has different HW and uCode, the behavior is also
different; these functions thus now form part of the ops infrastructure,
so we can have more control on how to monitor and recover from error condition
case per device.

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