staging: wilc1000: fix return type of wilc_init

This patch changes return type of wilc_init from s32 to int.
The error code as -ENOMEM or -EFAULT is returned in the wilc_init.
It is better to use return type of int in this function, not s32.

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