staging: wilc1000: remove unused variable rxq_thread

The rxq_thread never runs since it's kthread_run code was delete in a previous
patch. Remove kthread_run and it's related codes.

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