staging: wilc1000: rename pu8ssid in struct user_conn_req

This patch renames pu8ssid to ssid to remove pu8 prefix in struct
user_conn_req. There is no need to use prefix to show data type of this
variable.

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