connector/cn_proc: revert "connector: Fix proc_event_num_listeners count not cleared"

This reverts commit c46bfba1

 ("connector: Fix proc_event_num_listeners
count not cleared").

It is not accurate to reset proc_event_num_listeners according to
cn_netlink_send_mult() return value -ESRCH.

In the case of stress-ng netlink-proc, -ESRCH will always be returned,
because netlink_broadcast_filtered will return -ESRCH,
which may cause stress-ng netlink-proc performance degradation.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401112259.b23a1567-oliver.sang@intel.com
Fixes: c46bfba1

 ("connector: Fix proc_event_num_listeners count not cleared")
Signed-off-by: Keqi Wang <wangkeqi_chris@163.com>
Link: https://lore.kernel.org/r/20240209091659.68723-1-wangkeqi_chris@163.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>