staging: wilc1000: remove used functions

This patch remove unused functions add_handler_in_list and
remove_handler_in_list, and it's related global variable wfidrv_list and codes.
label fail_timer_2 and it's codes are removed since label is not used anymore.

Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>