staging: wilc1000: remove goto from wlan_initialize_threads

This patch remove goto feature from wlan_initialize_threads function.
Goto feature is 'wilc->close=0' & return result.
So, remove goto feature and it was replaced with the return value directly,
as well as removed unused ret variable.
Also, execute 'wilc->close=0' before return.

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