staging: wilc1000: use completion instead of struct semaphore hif_sema_thread

struct semaphore hif_sema_thread is used to signal completion of host
interface thread. This patch replaces struct semaphore hif_sema_thread
with struct completion hif_thread_comp. It is better to use completion
than semaphore for this case.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>