staging: wilc1000: handle remain on channel cfg ops from cfg80211 context

Refactor wilc_remain_on_channel() to handle remain_on_channel callback
from cfg80211 context.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>